path: root/Master/texmf-dist/source/generic/knuth/errata/errorlog.tex

% Appendix to the Errors of TeX paper (updated) 
% Section numbers now adjusted to TeX 3.0 equivalents
% NB: tab marks are significant in this file, they signal continuation lines
%\magnification=\magstephalf
%\pageno=35
\input logmac
* 10 Mar 1978
L1. Rename a few external variables to make their first six letters unique.
D2. Initialize \\{escape_char} to $-1$, not 0 [it will be set to the
	first character input]. @240
L3. Fix bug: The test `$\\{id}<\O{200}$' was supposed to distinguish one-letter
	identifiers from longer (packed) ones, but negative values of
	\\{id} also pass this test. @356
B4. Fix bug: I wrote `{\bf while} $\alpha\land(\beta\lor\gamma)$' when I meant
	`{\bf while} $(\alpha\land\beta)\lor\gamma$'. @259
R5. Initialize the input routines in |INITEX| [at this time a short,
	separate program not under user control], in case errors occur. @1337
E6. Don't initialize \\{mem} in |INITEX|, it wastes time. @164
B7. Change `\\{new_line}' [which denotes a lexical scanning state] to
	`\\{next_line}' [which denotes
	\\{carriage_return} and \\{line_feed}] in print commands.
F8. Include additional test `$\\{mem}[p] \ne 0\; \land$' in \\{check_mem}. @168
M9. Fix inconsistency between the \\{eq_level} conventions of \\{macro_def} and
	\\{eq_define}. @277
# About six hours of debugging time today.
# |INITEX| appears to work,
	and the test routine got through \\{start_input},
	\\{chcode} [the \TeX78 command for assigning a \\{cat_code}],
	\\{get_next}, and \\{back_input} the first time.
* 11 Mar 1978
I10. Insert space before `|(|' on terminal when opening a new file. @537
F11. Put `$p\gets \\{link}(p)$' into the loop of \\{show_token_list},
	so that it doesn't loop forever. @292
L12. Shift the last item found by \\{scan_toks} into the \\{info} field.
	[With |SAIL| all packing of fields was done by arithmetic operations,
	not by the compiler.] @474
B13\>12. Fix the previous bugfix: I shifted by the wrong amount. @474
I14. Add a feature that prints a warning when the end of a file page occurs within
	a macro definition or call. [System dependent.] @336
# Unintended bugs in my test routine [a format intended eventually to typeset
	{\sl The Art of Computer Programming\/}] helped check out the
	error recovery mechanisms.
	For example, I had `|\lft{#}|' instead of `|\lft{##}|' inside a macro,
	and three cases of improper |{|~and~|}| nesting.
F15. Add the forgotten case `\\{set_font}:' to \\{eq_destroy}. @275
C16. Change |\require| to |\input|. @376
F17. Add code for the case $\\{cur_cmd}=0$ [later known as the case
	`$\,t\ge\\{cs_token_flag}$'] when scanning a tokenlist. @357
# That's the first ``big'' error I've spotted so far.
I18. Introduce a `|d|' option in the error routine, to facilitate debugging. @84
L19. Assign a floating-point constant \\{ignore_depth} to \\{prev_depth},
	instead of assigning the integer constant \\{flag}
	[since \\{prev_depth} is type \\{real} in \TeX78]. @215
I20. Improve the readability and spacing of \\{show_node_list} output. @182,187
F21. Set the variable $v$ before using the {\bf case} construction in
	\\{show_node_list}, because there's one case where $v$ 
	didn't receive a value [as part of the field unpacking]. @182
# About seven hours today.
* 12 Mar 1978
# One hour to enter yesterday's corrections and recompile.
# At this point \TeX\ correctly located further unintended syntax errors
	in |acphdr| [the test file].
I22. Insert \\{debug_help} into \\{succumb}, giving a chance to look at memory
	before the system dies. @93
D23. Use \\{eq_destroy} wherever necessary in \\{unsave}. @283
L24. Change `$t \gets  (t-1)$ mod 8' to `$t \gets  (t-1)$ land~7' in \\{id_name},
	since |SAIL| has $-1$~mod~$8 = -1$. [At this time, \\{id_name} is a
	routine that unpacks control sequence names, according to a scheme
	that will become obsolete after change \#422.]
S25. Remove the space that appears at end of paragraph.
	(I hadn't anticipated that.) @816
L26. Throw away unwanted \\{line_feed} after getting a \\{carriage_return}
	in response to \\{in_chr_w} [a system routine for
	input from the terminal]. @83
B27. Delete spurious call to \\{flush_list} in \\{end_token_list}. @324
# Why did I make such a silly mistake?
F28. Fix bug in \\{get_x_token}: I forgot to say `\\{macro_call}' (which is the
	main point of that routine)! @380
# While tracking that bug down, I found out incidentally that kerning is okay.
# Also \TeX\ correctly caught an error |0p| for |0pt|.
L29. Fix bug in \\{scan_spec} ({\bf while} instead of {\bf repeat}). @404
M30. Make the table entries for |\hfill| and |\hskip| consistent with the
	program conventions. @1058
L31. Disable unforeseen coercion: When \\{scan_spec} put \\{hsize} on
	\\{save_stack}, the value changed from \\{real} to \\{integer}. @645
I32. Use `|*|' instead of `|-1.0|' for running dimensions
	of rules in \\{show_node_list}. @176
D33. Clear \\{mem}[\\{head}] to null in \\{push_nest} [in \TeX82, this
	will be done by \\{get_avail}]. @216
# A vrule link got clobbered because I forgot to do this.
I34. Translate ASCII control codes to special form when displaying them. @48,68
# Ligatures work, but \\{show_node_list} showed them funny.
F35. Remember to clear parameters off \\{save_stack} in \\{package} routine. @1086
# About eight hours today.
* 13 Mar 1978
D36. Introduce a new variable \\{hang_first} [later the sign of \\{hang_after}]. @849
E37\>36. Simplify the new code, realizing that if $\\{hang_indent}=0$ then
	\\{hang_first} is irrelevant. @848
# Time sharing is very slow today, so I'm mostly reading technical reports while
	waiting\/ {\bf three hours} for compiler, editor, and loading routine.
# I'm not counting this as debugging time!
# (Came back in the evening.)
P38. Spruce up the comments in the \\{line_break} routine, which appears to be
	almost working. @813
D39. Rethink the setting of \\{best_line}; it's 1 too high in many cases.
	[The final line of a paragraph was handled in a treacherous way.] @874
D40. Compute proper initialization for
	\\{prev_depth} when beginning an |\hbox|
	with a paragraph inside. [This refers to a special `paragraph box'
	construction, used when an hbox of specified size becomes overfull;
	\TeX78 doesn't have the concept of internal vertical mode.] @1083
D41. Also initialize \\{tail} in that case. @1083
M42. Also put the result of line-breaking into the correct list.
T43. Fix a typo in the \\{free_node} routine (`\\{link}' not `\\{llink}');
	by strange chance it had been harmless until today. @130
F44. Fix bug: \\{post_line_break} forgot to set \\{adjust_tail}. @889
D45. Update \\{act_width} properly when looking for end of word while
	line breaking. @866
B46. Repair the ``tricky'' part of \\{get_node}: I used the \\{info} field
	when I meant to say \\{llink}. @127
# Now the |\corners| macro of |acphdr| works! [See |\setcornerrules|
	in {\sl The \TeX book}, page 417.]
D47. Reset \\{contrib_tail} properly in \\{build_page}. @995
T48. Fix typo (|-| for |+|) in computation of \\{page_total}. @1004
S49. Change the page-breaking logic: \TeX\ reached \\{fire_up} with
	$\\{best_page_break}=\\{null}$ in one case,
	since the badness was too bad. @1005
M50. Perform the operation \\{delete_token_ref}(\\{top_mark}) only when
	$\\{top_mark}\ne0$. @1012
F51. Make \\{scan_toks} omit the initial |{| of an |\output| routine. @473
I52. Insert a comma to make memory usage statistics look better. @639
# About seven good hours of debugging today.
# Tomorrow will be first-output day (I hope).
* 14 Mar 1978
# (Came in evening after sleeping most of day, to get computer at better time.)
# (Some day we will have personal computers and will live more normally.)
# 8:30pm, began to enter corrections to yesterday's problems.
I53. Issue an error message for non-character in filename or in font name. @771
I54. Display `|...|' for omitted stuff in \\{show_context} routine. @643
L55. Watch out for the |SAIL| syntax `$\alpha+\beta\mathbin{\rm lsh}\gamma$';
	it doesn't shift $\alpha+\beta$ left (only $\beta$). @464
# That error was very hard to track down; it created a spurious link field
	and sent $\\{hash}[0]=\null$|\beta| to the scanner!
# I could have found this bug an hour sooner if I had looked at the correct
	stack entries for \\{name} and \\{token_type}.
D56. Show the correct page number when tracing pages before output is shipped. @638
F57. Remember to nullify a box after using it. @1079
I58. Issue an error message if\/ |\box255| isn't consumed by the output routine. @1015
# I'm having trouble with the |BAIL| debugger;
	it makes an illegal memory reference and dies,
	when single-stepping past the entry to recursive procedures
	\\{hlist_out} and \\{vlist_out}.  So I have to reload and be careful
	to go thru these procedures at high speed.
P59. Fix bug in comment (memory parameter description said $\ge$ not $\le$). @11
B60. Fix typo in definition of rule output (said $x,y$ not $\\{x0},\\{y0}$).
	[This part of the code went away when |DVI| files were introduced.]
B61. Correct the embarrassing bug in shellsort, where I said `$\le\\{str}[k]$'
	not `$\le t$'.
	[The first \TeX\ had to sort all output by vertical position on page.]
M62. Make \\{start_input} set up \\{job_name} in the form needed by \\{shipout};
	it uses obsolete conventions. @532,537
L63. Insert |(| and |)| into the |SAIL| macro definition of \\{new_string}.
	[This macro was for pre-|DVI| output.]
M64. Unscramble the parameters of \\{out_rule}:
	The declaration was $(\\{x0},\\{y0},\\{x1},\\{y1})$
	while the call was $(\\{x0},\\{x1},\\{y0},\\{y1})$.
# 4:30am, \TeX's first page is successfully output!
# (It was `|\titlepage\setcpage1\corners\eject\end|'.)
* 15 Mar 1978
# 10:30pm. Today I'm instrumenting the line-breaking routine and putting it
	through a bunch of tests.
# (The inserted instrumentation had bugs that won't be mentioned here.)
C65. Don't abort the job when \\{eq_destroy} redefines a
	\TeX\ control sequence. @275
# The first word of a paragraph won't be hyphenated \dots\ so be it!
T66. Fix the typo in \\{line_break} that spoils the test for
	`letters in the same font'. @896
# The effect of that typo was to suppress all hyphenation attempts.
B67\>25. Replace the space at paragraph end by fillglue, not by zero. @816
L68. Pack the hyphen character properly into its node. @582
T69. Fix a typo (`{\tentex\char'30}' for `|+|')
	in the computation of \\{break_width}. @838
M70. Change the |\end| maneuver; the present code doesn't end the job,
	since I forgot that \\{back_input} uses \\{cur_tok}. @1054
A71. Add a parameter to \\{try_break}, since the width is different at
	a discretionary hyphen. [This problem will be solved differently in \TeX82,
	when discretionaries become much more general.] @840
F72. Bypass kern nodes in pre-hyphenation. @896
F73. Supply code for the forgotten case `$<$ |"a"|' in pre-hyphenation.
	[This case was later generalized to a test of \\{lc_code}.] @897
B74. Change $\\{mem}[q]$ to $\\{prev_break}(q)$ in the
	reverse-linking loop. @878
# (Such blunders. Am I getting feeble-minded?)
A75. Introduce special logic for \\{eject_penalty}; I was wrong
	to think that forced ejection was exactly like an
	infinitely negative penalty. @851
A76. Use $(1+b)^2-p^2$ when computing demerits with $p<0$. @859
# 6:30am. The line-breaking algorithm appears to be working fine
	and efficiently.
	On small measures (about 20 characters per line), it gives overfull boxes
	instead of spaced out ones. Surprising but satisfactory.
* 16 Mar 1978
# 9pm. The plan for tonight is to test page breaking and more paragraphing.
G77. Insert `|\topskip|' glue at beginning of page. @1001
I78. Add `|\pausing|' feature. @363
M79. Fix discrepancy: In \\{make_accent} I called \\{vpackage}
	with a pointer to the first list item, but \\{vpackage} itself assumes
	that the parameter is a pointer to that pointer. [The
	\\{vpackage} of \TeX82 will be different.] @668
# I checked for other lapses like that. Result: 14 calls OK, 12 NG.
M80. Create a new temporary list head location, \\{hold_head}, since there's
	a case where \\{vpackage} is improperly called with
	parameter \\{temp_head}. [At this time \\{vpackage} uses \\{temp_head}
	to make a list of all insertions found.] @1014
# 11:30pm. The machine is tied up again.
F81. Write code to handle charnodes in vlists; I forgot that I'd decided
	to allow them. [Later I prohibited them again!] @669
F82. Combine the page lists before pruning off glue
	in \\{fire_up}; otherwise the pruning doesn't go far enough. @1017
B83\>25. Fix typo where line-breaking starts: `\\{fill_glue}' should be
	`\\{new_glue}(\\{fill_glue})'. @816
I84. Add |/q| to |xspool| command (cosmetic change). [This changes a system
	command that causes \TeX\ output to be printed on the Xerox Graphics
	Printer (XGP), the progenitor of future laser printers;
	the |/q| option says that the queue of printing requests should be
	displayed on the user's terminal.] @642
E85. Don't write a form feed after the last page of output. @642
# To fix this, I reorganized \\{ship_out}, and it became simpler.
T86. Correct a typo (`{\tentex\char'30}' for `|+|') in the \\{vlist_node} case
	within \\{hlist_out}. [The output routines were quite different
	at this time, because output went directly to the XGP.] @622
I87. Change the message `|completed page|' to `|Completed for page|'. @638
B88\>48. Fix yet another typo in the computation of \\{page_total}: My original
	code said $\\{stretch}(p)$ instead of $\\{stretch}(q)$ (terrible). @1004
P89. Document the dirty trick about \\{bot_mark}'s reference count.
	[That trick is, fortunately, no longer useful.] @1016
A90. Rethink the algorithm for contributing an insertion: The original code
	tests for a page break after incrementing the totals but
	before the \\{contrib_list} is updated. [\TeX78 handles insertions
	in a hardwired manner that will be greatly generalized in \TeX82.]
F91. Fix \\{get_node} again:
	After the variable memory overflows, control falls through to \\{found}
	instead of going to the \\{overflow} call. @125
# I spent several hours tracking down that data structure bug!
B92. Change \\{new_line} to \\{next_line} in yet another print command (see \#7).
A93\>75. Amend the line-breaking algorithm:
	|\break| in paragraph doesn't work with really bad breaks. @851
# A problem to be diagnosed tomorrow: Each time I run the test program,
	the amount of memory in use grows by 13 cells not returned.
# Seven hours tonight.
* 17 Mar 1978
G94. Introduce \\{dead_cycles} to keep |\end| active until \\{ship_out}
	occurs. @1054
E95. Don't call \\{line_break} with an empty list. @1096
S96. Take proper account of the (infinite) fillglue when computing
	the width of a paragraph line preceding a display. @1146
M97. Add a new parameter to \\{hpack} so that \\{line_break} won't be called
	at the wrong time.
	[This is for the soon-to-be-obsolete feature described in \#40.]
L98. Give a warning message if there's an |\hfill| in the middle of a paragraph;
	fillglue upsets the line breaker,
	because floating-point calculations don't have sufficient accuracy. @868
# I spent an hour looking for another bug in \TeX, but the following one was in \MF:
	The \\{xgp_height} data in fonts had been supplied wrong.
# It took two hours to recompile 32 fonts with proto-\MF.
R99. Make \\{show_node_list} and \\{show_token_list}
	more robust in the presence of software bugs. @182
D100\>97. Do not remove nodes with \\{eject_penalty},
	when the new parameter to \\{hpack} is \\{true}.
E101\>97. Put a fast exit into \\{hpack}; e.g., at glue nodes, test `{\bf if}
	\\{paragraphing} $\land$ $\langle$current width is large$\rangle$'.
# 2am. I have to go to bed ``early'' tonight.
* 18 Mar 1978
# 3:30pm. (Saturday)
I102. Add a parameter to \\{check_mem} (to suppress display unless needed). @167
G103. Introduce a user-settable parameter |\maxdepth|, and
	pass it as a parameter to \\{vpackage}. @668
# I realized the need for |\maxdepth| while fixing insertions (see \#90).
G104. Introduce a user-settable parameter for \\{line_break}: The constant
	2.0 in my original algorithm becomes |\jpar|
	[later |\tolerance|], to be set like |\tracing|. @828
D105. Reclaim the \\{eject_penalty} nodes removed during line-breaking. @879
# (Those were the 13 extra nodes reported on Thursday.)
# The \\{init_align} procedure worked right the first time!
# Also \\{init_row}, \\{init_col}. But then\thinspace\dots
S106. Rethink the command codes: \\{endv} in a token list has too high a
	code for the assumptions of \\{get_next}. @207
A107. Add a \\{prev_cmd} variable for processing delimited macro parameters;
	the original algorithm loses track of braces.
	[The rules will change slightly in \TeX82, and
	\\{rbrace_ptr} will take on a similar function.] @400
S108. Make the \\{get_next} routine intercept |&| and |\cr| tokens. @342
# I'd thought I could just put |&| and |\cr| into
	\\{big_switch} [i.e., in the stomach of \TeX, not the eyes];
	that was a great big mistake.
R109. Make more error checks on \\{endv}; e.g., it must not occur in
	a macro definition or call. @780
S110\>108. No, rethink alignments again; the new program still fails! @768
# For the first time I can glimpse the
	hairiness of alignment in general (e.g., `|\halign{\u#\v&...|'
	when |\u| and |\v| are defined to include |&|'s and possible
	alignments themselves).
# I think there's a ``simple'' solution, by considering only whether
	an alignment is currently active [in \S342].
# 11:30pm. Went to bed.
* 19 Mar 1978
# Woke up with ``better'' idea on how to handle |&| and |\cr|.
# (Namely, to consider a special kind of\/ |\def| whose parameters don't interrupt
	on |&|'s and |\cr|'s.)
# But replaced this by a much better idea (to introduce \\{align_state}).
# 11pm. Began to use computer. Performed major surgery
	(inserting \\{align_state} and updating the associated routines
	and documentation).
D111. Pop the alignment stacks in \\{fin_align}. @800
T112\>110. Fix a (newly inserted) typo in \\{show_context}. @314
D113\>110. Set \\{align_state} false when a live |&| or |\cr| is found.
	[Originally \\{align_state} was of type \\{boolean}.] @789
I114. Insert |\cr| when `|}|' occurs prematurely in an alignment. @1132
M115. Remember to record \\{glue_stretch} when packaging an unset node. @796
# I had a mistake in |acphdr| definition of\/ |\quoteformat|; also extra spaces.
# My first test programs, used before today, were contrived to test macro
	expansion, line-breaking, and page layout.
# Next I'm using a test program based on Volume 2.
C116. Make carriage-return, space, and tab equivalent for macro matching. @348
F117. Omit the reference count node when displaying a mark. @176
B118. Correct a silly slip: I wrote `\\{type_displacement}' instead of
	`\\{value_displacement}' when packing data in a penalty node. @158
M119. Don't go to \\{build_page} after seeing |\noindent|; \TeX\ isn't
	ready for that.
	[In the original program, this was an instance of a bad {\bf goto}.] @1091
# I had undesired spaces coming thru the scanner in my macro definitions
	of\/ |\tenpoint| [see {\sl The \TeX book}, page 414].
# 4am. \TeX\ now knows enough to typeset page 1 of Volume 2!
# Also it did its first ``math formula'' (namely `|$X$|') without crucial error.
# (Except that the italic correction was missing for some reason.)
D120. Remember to decrement \\{cur_level} in \\{fin_align}. [The routines will
	eventually become more general and use \\{unsave} here.] @800
D121. Remember to increment \\{cur_level} in error corrections by
	\\{handle_right_brace}. [A better procedure will be adopted later.] @1069
T122. Fix a typo: (`|{|' instead of `|}|') in error message for $\\{mmode}+
	\\{math_shift}$. @1065
R123\>99. Make \\{show_noad_list} more robust and more like the new
	\\{show_node_list}. [The routines will be combined in \TeX82.] @690
L124. Fix a typo in \\{char_box}: should say \\{font_info_real}.
	[In \TeX78 a single array
	is used for both \\{real} and \\{integer}; in \TeX82 things will be
	\\{scaled}.] @554
B125. Fix typos in the definitions of \\{default_rule_thickness} and
	\\{big_op_spacing}; they shouldn't start at \\{mathex}(7). @701
B126. Reverse the \\{before} and \\{after} conventions in math nodes. @1196
# I had them backwards; this turned
	hyphenation on just before math, and off just after it!
# Seven and a half hours debugging today.
	Got through the test program a little more.
	But \TeX\ blew up on `|$Y+1$|'; tomorrow I hope to find out why.
* 20 Mar 1978
# 8pm. I decided to work next on a super-hairy formula.
C127. Change `|\ascii|' to `|\cc|' (character code). [This name will change again
	later, to `|\char|'.] @265
E128. Don't bother to store a penalty node at the beginning of |$$| when
	the paragraph-so-far fits on a single line, since such a penalty
	has already been stored. [These conventions will change later, and
	the |\predisplaypenalty| will always be stored.] @1203
S129. Avoid reference to \\{tail} in \\{build_page},
	if $\\{nest_ptr}>0$. @995
B130. Correct a silly
	slip in \\{math_comp} (the exact opposite of what I did in \#118). @1158
B131. Rectify my mental lapse in \\{make_fraction}; I said \\{nucleus} instead of
	\\{thickness}. @743
F132. Mask off the math class when scanning delimiters. @1160
C133. Allow an optional space after |\def{...}|. [This decision
	will be retracted later.] @473
# My test example is so complicated it causes the semantic stacks to overflow!
L134. Don't test for no pages output by looking at the channel status. @642
T135. Fix typo in definition of\/ |\mathop| (\\{open_noad} not \\{op_noad}). @1156
A136. Rewrite \\{fin_mlist}, because `|\left(...\above...\right)|' doesn't
	parse correctly; the |\left| goes into the numerator,
	the |\right| into the denominator. @1184
B137. Correct the use of \\{depth_threshold} in \\{print_subsidiary_data}:
	Simple fields get shown while others look empty. @692
I138\>78. Return the carriage before showing the first line of a new file
	when pausing. @538
M139. Fix bug: The call \\{show_noad_list}(\\{mem}[|..|]) should be
	\\{show_noad_list}(|..|), in the \\{incompleat_noad} case
	of \\{show_activities}. @219
# 3am. The whole messy formula has been parsed correctly into a tree.
# The easy part is done, now comes the harder part.
F140. Don't shift single characters down in \\{make_op}. @749
D141. Make \\{clean_box} return a box (as its name implies), not an hlist. @720
# Font info still isn't quite right, it has the wrong value of \\{quad}.
A142. Retain the italic correction when doing \\{rebox};
	can make $\\{glue_set}\ne0$ a flag for this. [A better
	solution will be adopted later.] @715
B143. Fix the bug that makes \\{rebox} bomb out: $\\{value}(p)$ should be
	$\\{value}(\\{mem}[p])$. @715
# 6am; ten hours today. \TeX\ didn't do |$\pi\over2$| correctly, but was close.
# I found that the \\{rebox} problem (\#142) went away when I fixed the
	\\{clean_box} problem (\#141); but I
	will leave the extra stuff about $\\{glue_set} \ne 0$
	in the program anyway, just for weird cases.
E144. Omit extra levels of boxing when possible in \\{clean_box}. @721
# (To do this, I need to face the \\{rebox} problem anyway.)
* 21 Mar 1978
# 10pm. The computer is rather heavily loaded tonight.
F145. Don't forget \\{thickness} when making a square-root sign (see \#131).
	[The rule thickness will later be derived from the character height.] @737
L146. Define $p$ local to the \\{make_fraction} routine. @743
# Unwittingly using the global $p$ was a disaster.
I147. Don't show the amount of \\{glue_set} when it's zero. @186
D148\>142. Make \\{glue_set} nonzero in the result of \\{var_delimiter}. @706
F149. Fix bug: The \\{math_glue} function didn't return any result. @716
T150. Fix typo in \\{char_box} ($c$ not $w$); this caused a subscripted~$P$ to come
	out the same width as an unsubscripted~$P$. [Later changes in the rules
	will move this computation to \S755.] @709
P151\>144. Revise \\{clean_box} to do operations that are needed
	often because of the \\{rebox} change. @720
D152. Use the new \\{clean_box} to avoid a bug in |\sqrt{\raise...}|. @737
Q153. Change the definition of\/ |\not| so that it's a relation
	(which will butt against the following relation). [All math
	symbols and Greek letters are defined in |INITEX| at this
	time, not in a changeable format definition.]
I154. Give error message `{\tt Large delimiter must be
	in mathex font}', instead of calling \\{confusion},
	since the error can occur.
	[This particular error is impossible in \TeX82.] @706
F155. Change the use of $p$ in \\{var_delimiter}; it isn't always set when I say
	{\bf goto} \\{found}. @706
# Another font problem now surfaced: The mathex meta-font didn't compute \TeX\ info
	in a machine-independent way.
	(It took two hours to correct this.)
D156. Don't forget to set $\\{type}(b)$ in all relevant cases of
	\\{var_delimiter}. @708
B157. Use the correct sign convention for \\{shift_amount} in \\{hpackage}. @653
F158. Always kern by \\{delta} when there's no superscript. @755
M159. Declare \\{space_table} to be $[0\,.\,.\,6,0\,.\,.\,6]$
	not $[0\,.\,.\,7,0\,.\,.\,7]$; otherwise its entries are
	pre\-loaded into the wrong positions. [The \\{space_table} in \TeX78 is
	$7\times7$; it will become $8\times8$ in \TeX82,
	represented as a string called \\{math_spacing}.] @764
C160. Use a negative value, not zero, to represent a null delimiter.
	[Actually zero will come back again later.] @685
C161\>127. Change |\cc| to |\char|. @265
L162. Don't use tricky subtraction on packed data when changing $q$ to
	an \\{ord_noad} in \\{mlist_to_hlist}; subtraction isn't always safe. @729
B163. Fix two typos in the \\{space_table} (|*| for |0|). @764
F164. Initialize \\{cur_size} everywhere (I forgot it in two places). @703
A165. Reset \\{op_noad} before resetting \\{bin_noad}. @728
F166. Treat $\\{display_style}+\\{cramped}$ the same as \\{display_style}
	inside \\{make_op}. @749
B167. Shift the character correctly in the non-|\displaystyle| case of
	\\{make_op}. @749
# Still another font problem: The italic corrections are wrong because
	the corresponding array was declared \\{real} in proto-\MF\ (and
	italic corrections were used in nonstandard way in |mathex|).
B168. Use \\{depth} instead of \\{height} in \\{var_delimiter}.
	[Later, both were used.] @714
Q169. Skew the accents according to the font \\{slant}. [Soon retracted.] @741
# At this point I think nearly all the math routines have been exercised.
# Tomorrow they should work!
# Eight hours debugging today.
* 22 Mar 1978
# (Wednesday, but actually Thursday:
	I began at midnight because I was proofreading a paper.)
# I checked out the font access tables, slowly (i.e., all the |\mathcode|
	and special-character name entries were catalogued).
Q170\>169. Do {\bf not\/} consider slants after all in the math accent
	routine, since slanted math letters are put differently into fonts. @741
B171. Don't use $q$ for two different things simultaneously
	in \\{make_math_accent}. @738
F172. Fix bug in \\{compact_list} (I forgot to advance the loop variable).
	[This procedure became unnecessary in \TeX82.]
M173. Avoid conflict between \\{var_delimiter} and \\{mlist_to_hlist}, which
	want to use \\{temp_head} simultaneously. @713
T174. Fix bad typo in \\{overbar} routine ($b$ for $p$). @705
# Finally \TeX\ got to \\{after_math} after dealing with that
	hairy formula\thinspace\dots
T175. Fix another bad typo: $p$ for $b$ this time. @1199
L176. Insert more parentheses (twice) because of `|lsh|' precedence
	in |SAIL|. @1199
M177\>36. Use the new hanging-indentation conventions when formatting displayed
	equations. @1199
Q178. Recompute penalties so that break is allowed after \\{punct_noad}s. @761
F179. Center the large delimiters vertically. @749
Q180. Round all rule sizes (up) before drawing them. @589
Q181. Provide more space over $x$ in $\sqrt x$, and more space atop vincula.
	@705,737
Q182. Make large delimiters large enough to cover formula height
	(important for subscripts, superscripts). @762
I183. Insert |/ntn=33| on XGP prompt message so that complex math
	won't blow the device driver. [See \#84.]
P184\>161. Update the comment about the meaning of\/ |\char|, since it
	can be used in math mode. @208
# Six hours today.
* 23 Mar 1978
# 11pm, Maundy Thursday.
C185\>104. Make |\tracing| and |\jpar| follow block structure. @283
# It took me two hours to enter yesterday's corrections,
	because the changes were so numerous.
M186. Fix bad call on \\{begin_token_list} when marks are to be scanned. @396
# Now the formula looks like it should, modulo problems in fonts.
Q187. Prevent an exponent from going below baseline + xheight/4. @758
B188. Change \\{quad} to \\{math_quad} when finishing a display
	(several places). @1199
A189. Don't use \\{append_to_vlist} when putting an |\eqno| box on a separate
	line, because the page shouldn't break at glue there.
	[Later, the \\{append} will be used but preceded by an
	infinite penalty.] @1205
S190. Increase the input \\{stack_size}; \TeX\ may need to back up a lot. @11
A191. Don't assume that $p$ always points to a glue node when
	a page is broken. @1017
A192. Use \\{epsilon} in \\{scan_spec} (I had used a different
	small constant). [This was a kludge to avoid the extra
	parameter later called \\{exactly} or \\{additional}.] @645
R193. Introduce a new procedure \\{scan_positive_length}, to prevent
	negative or zero lengths in \\{scan_rule_spec}.
	[This restrictive rule will be ``overruled'' later.] @463
B194. Fix ridiculous bug in the leaders routine of \\{vlist_out}:
	I had the initialization {\sl inside\/} the loop! @635
L195. Eliminate confusion between the two temp variables named $h$;
	one is \\{real} and the other is \\{integer}. @629
F196. Include forgotten case (\\{leader_node}) in \\{hlist_out}.
	[Type \\{leader_node} will be absorbed
	into \\{glue_node} in \TeX82.] @622
F197. Don't forget to compute \\{x0} in variable horizontal rules. @624
# Seven and a half hours today.
# \TeX\ seems to be ready to tackle my test file based on Volume 2.
S198. Calculate \\{y00} in horizontal rules as an integer number of pixels
	from the baseline, so that the baseline doesn't jump. @589
* 25 Mar 1978
# 2am Saturday. (Might as well drop Friday.)
D199\>185. Make \\{def_code} consistent with the new |\tracing| conventions.
	[Many tracing options are packed into a single
	parameter called |\tracing|.] @1233
R200\>185. Don't allow users to change nonexistent things like |\catcode1000|. @1232
F201\>110. Reset \\{align_state} at beginning of \\{init_align}. @774
F202. Don't forget \\{scan_left_brace} after |\noalign|. @785
F203\>110. Set $\\{cur_cs}\gets 0$ in \\{get_next}, after |\cr|
	causes a switch to the $\langle v_j\rangle$ template. @342
# Ouch, that was a big bad bug, which took me three hours to find
	(since I thought \TeX's low-level scanning mechanism was working).
# Note to myself: I\/ {\bf knew\/} it would be cleaner to define \\{get_next}
	so that it sets \\{cur_cs} to zero every time it begins [i.e.,
	in \S341, where this change will in fact be made in \TeX82].
	But I had avoided this on grounds of efficiency in the inner loop.
	Well, now I have earned this tiny bit of efficiency.
D204. Prohibit the first word of an unavailable node from becoming negative.
	[The storage allocator of \TeX78 uses
	a negative value to signify a node that is available, just as
	`$\\{link}=\\{max_halfword}$' will signal availability in \TeX82.] @124
# That was another bad one, it's not my night.
# At least I'm developing more subtle diagnostic techniques.
M205. Remember to un-negate the top \\{save_stack} entry
	when \\{handle_right_brace} finishes an \\{insert_group}.
	[This routine was completely revised in \TeX82.] @1100
F206\>185. Initialize |\jpar| [i.e., |\tolerance|]. @240
B207. Correct the display of insertion nodes by \\{show_node_list}. @188
R208. Prevent \\{show_token_list} from generating really long strings
	when in a loop. @292
D209. Increase the reference count of \\{bot_mark} when
	\\{vpackage} finds it. [This was later the job of \\{fire_up}.] @1016
M210. Remember that the tokenlist for a mark ends with a |}|. @1101
D211. Don't let \\{vpackage} lose the top insert. (It fails when
	the very first item is a |\topinsert|.) @1014
A212. And when that stupid code is corrected, make it handle
	insertions first-in-first-out. @1018
# Seven hours today.
* 26 Mar 1978
# Easter Sunday, will work till sunrise.
I213. Add an `|i|' feature to the \\{error} recovery routine. @87
I214. Include a prompt. @87
C215. Ignore space after |\noalign{...}|. @1133
# Otherwise, things are going well tonight;
	I'm finding more bugs in my test program than in \TeX.
# The `|i|' feature is proving to be very helpful.
# I increased the size of \\{mem}
	(now $\\{lo_mem_max}=3500$, $\\{mem_max}=10000$).
# In fact I just needed to increase it again
	(now $\\{lo_mem_max}=4500$, $\\{mem_max}=11000$).
R216. Make |INITEX| output \\{mem_top} for consistency checking. @1307
A217. Calculate the size of delimiters by considering the enclosed formula's
	distance from the axis, not from the baseline. @762
# I'm having trouble with a |SAIL| compiler bug; I must rearrange the program,
	more or less at random, until it
	compiles correctly. I hope the bug isn't more severe than it appears.
D218\>210. Don't put a new group on \\{save_stack} if a null mark is expanded.
	[\TeX82 will remove the `|}|' from the mark text.] @386
# I had to redo the typewriter-style font since its width tables were wrong.
# And I increased low-memory size again to 5500, then 6500.
# Finally the entire test program was \TeX ed. Happy Easter! Six hours today.
* 27 Mar 1978
# Beginning at 2:30am.
A219. Move |\vcenter| processing to the first pass of \\{mlist_to_hlist};
	otherwise the height, depth, subscripts, etc., are way off. @733
C220. Omit space after closing |$$|. @1200
# Spacing is wrong in the formula $Y_1+\cdots+Y_k$; I have to rethink the use
	of three dots.
G221. Make conditional thin space available to user as |\|{\tentex\char'34}.
	[Later will retract this.] @226
Q222. Introduce |\dispaskip| and |\dispbskip| [later called
	|\abovedisplayshortskip| and |\belowdisplayshortskip|]. @226
# Reminder: I need to test line-breaking with embedded math formulas.
I223. Make sure that $\\{interaction}\ne\\{error_stop_mode}$
	in the `|Whoa|' error [\\{fatal_error}]. @93
B224. Fix a big mistake in the \\{style_node} routine (which points to a glue spec,
	not to glue itself); somehow this didn't cause trouble yesterday.
	[In \TeX78, style nodes double as placeholders for math glue
	like thin spaces.] @732
C225. Make |\fntfam| obey group structure. [\TeX78's |\fntfam| operation
	is a combination of \TeX82's
	|\textfont|, |\scriptfont|, and |\scriptscriptfont|.] @1234
# At this point the test routine for Volume 2 works perfectly.
# But I will change the page width in order to check harder cases.
Q226\>178. Disable automatic line breaks after punctuation in math
	(e.g., consider $f(x,y)$). @761
S227. Represent italic corrections as boxes, not glue, so that they won't be broken.
	[The |\kern| command doesn't exist yet.] @1113
# Eight hours today.
B228. Fix a bug that just clobbered the memory: Call \\{free_avail}, not
	\\{free_node}, in the \\{ins_node} case of \\{vpackage}.
	[This logic will change completely in \TeX82.] @1019
* 29 Mar 1978
# (Wednesday) Again beginning at 2:30am.
Q229. Put still more space above and below fraction lines in displayed
	formulas. @746
G230\>189. Install an infinite penalty feature, which positively suppresses breaks;
	use it in displayed formulas whose |\eqno| doesn't fit. @1205
F231. Call \\{build_page} after finishing a display; and don't
	go to the |\noindent| routine because of the next remark. @1200
S232. Put |\parskip| glue just before a paragraph, not just after
	(since it interferes with a penalty after). @1091
# Although the test program gives correct output, it generates 46 locations
	of variable-size memory and 280 of one-word memory that are not freed.
F233. Recycle the ulists and vlists in \\{fin_align}. @801
M234\>25. Fix bug when deleting space at end of paragraph:
	\\{delete_glue_ref}(\\{cur_node}) not
	\\{delete_glue_ref}(\\{value}(\\{cur_node})). @816
# There's also a more mysterious type of uncollected garbage,
	a \\{fraction_noad} corresponding to
	|$p\choose$|, an \\{incompleat_noad} not completed.
# Couldn't find that one, so I recompiled with \#233 and \#234 corrected.
# Now it gains just 10 locations of variable-size memory and 7 of the other kind.
I235. Extend \\{search_mem} to search \\{eqtb} also. @255
D236\>143. Fix bug in \\{rebox} when $\\{list_ptr}(b)=0$. @715
# The seven one-word nodes were generated by this bug;
	\\{rebox}\kern-1pt\ put them onto a linked list starting with
	$\\{mem}[0]$, growing at the far end!
D237. Remember to complete each \\{incompleat_noad}. @1184
# This solved the other mystery. I had never noticed that my test output
	was actually wrong: |$p\choose k$| came out as `$k$'.
# After these corrections, the test routine worked\thinspace\dots\ I feel
	that \TeX\ is now pretty well debugged
	(except perhaps for error recovery)---it's time to celebrate!
* 1 Apr 1978
I238. Don't quit after file lookup fails. @530
* 2 Apr 1978
P239. Add \\{\TeX_font_area}, so that it's easier to change the
	default library area associated with a device. @514
* 3 Apr 1978
L240. Insert parentheses again, to cope with the precedence of\/ |lsh|
	when packing data. (See \#55 and \#176.) @1114
# I had never tried $\\{hmode}+\\{discretionary}$ before!
M241. Remember that \\{back_error} requires \\{cur_tok} to be set.
	(Problem can arise during error recovery on parameter |#|$n$
	with $n$ out of range.) @476
* 4 Apr 1978
I242. Add a deletion feature to the \\{error} routine. @88
* 5 Apr 1978
Q243. Reset \\{space_factor} after |\/| [this was later rescinded]
	and after math in text. @1196
* 10 Apr 1978
G244\>104. Replace |\jpar| and |\tracing| by a new primitive |\chpar| for parameters.
	It allows a user to change those quantities as well as the penalties for
	hyphens, relations, binary ops, widows. @209
* 14 May 1978
# Beginning to typeset a real book (Volume 2, second edition), not just a test.
Q245. Make math in text end with spacing as if it were
	followed by punctuation. [This rule will soon be rescinded.] @760
F246. Insert |\times| into the hash table; I left it out by mistake.
	[It will eventually move into |plain.tex|.]
C247. Change the names of Scandinavian accents from |\o|, |\oslash|,
	|\Oslash| to |\a|, |\o|, |\O|. [This will also move to |plain|.]
* 17 May 1978
B248. Fix a silly bug that hasn't been tweaked until today:
	`|\halign to size|' [obsolete in \TeX82] used \\{vsize}
	instead of \\{hsize}. @645
* 19 May 1978
G249. Add a |\topbaseline| feature [later called |\topskip|]. @1001
Q250\>245. Subtract the math spacing change of May 14. @760
A251. Skip past blanks in the \\{scan_math} procedure. [This blank-skipping
	will eventually go into \\{scan_left_brace}.] @403
I252. Introduce a \\{missing_brace} routine [later generalized] to improve
	error recovery in $\\{mmode}+\\{math_shift}$, when the top
	of \\{save_stack} isn't a \\{math_shift_group}. @1065
Q253. Adjust the math spacing between closing parentheses and
	Ord, Op, Open, Punct. @764
Q254. Make the underline go further under. @735
S255\>96. Compute the proper natural width when a displayed equation follows
	a paragraph whose fillglue has been deleted by \\{line_break}. @1146
* 20 May 1978
A256. Fix the spurious value of \\{prev_depth} inside alignments. @775
S257. Consider (and defeat) the following scenario:
	The u and v lists are built in \\{init_align} using \\{temp_head};
	then while scanning `|\tabskip 2pt\rt{...}|' the macro |\rt| is expanded,
	clobbering \\{temp_head}. @779
# That bug was more subtle than usual.
Q258. Add the parameter \\{num3}, so that the positioning of\/ |\atop|
	can be different from that for fractions. @700
Q259. Add new parameters \\{delim1} and \\{delim2}, so that
	|\comb| can use fixed size delimiters, not computed as with |\left|. @748
* 22 May 1978
C260\>221. Change |\|{\tentex\char'34} to |\|{\tentex\char'35} and introduce
	|\|{\tentex\char'34} as the negative of\/ |\|{\tentex\char'35}.
	[Later obsolete.] @226
L261. Fix the display of negative penalty nodes; \\{show_node_list} is confused
	when a negative value has been packed into the middle of a word. @194
# Memory overflow just occurred with $\\{lo_mem_max}=7500$ and $\\{mem_max}=16384$.
	So I have to go to 15-bit pointers. (A problem on 32-bit machines?)
* 23 May 1978
Q262. Add a new parameter \\{big_op_spacing5}, for
	extra space above and below limits of big displayed operators. @751
F263. Initialize \\{incompleat_noad} in |$$\halign{...}$$|. @775
# That was another heretofore-untested operation. How much of the code
	has not yet been exercised?
F264\>238. Close the file when doing lookup-failure recovery. @27
I265. Improve the error recovery for `|Extra &|'. @792
R266. The top piece must be calculated mod 128 in \\{var_delimiter},
	to guarantee a valid subscript range. [Obsolete in \TeX82.] @546
B267\>252. Fix a blunder in new \\{missing_brace} code. @1065
B268\>262. Fix a blunder in new code for limits on display operators. @751
* 26 May 1978
Q269. Don't insert a new penalty after an explicit penalty in math mode. @767
# The hash table overflowed; I ought to make it much bigger.
R270\>110. Avoid possible bad memory references in alignment
	when there is erroneous input after |\cr|. [Instead of
	\\{extra_info}, the value of \\{cur_align} in \TeX78 is negated,
	because we need only distinguish |\cr| from |&|.] @789
S271. Make the dimension parameters like |\hsize| all global, so that they can
	be set in the |\output| routine. @279
# This led to major simplifications, also to major surgery.
# [But it was a kludgy decision, overruled in \TeX82.]
D272\>94. Don't forget to set the type of the new null box in the |\end| routine. @1054
* 27 May 1978
# The data overflowed memory again, both low and high, doing Section 3.3.2.
R273\>184. Mask off extra bits of\/ |\char| in math mode,
	to avoid bad memory references. @1151
B274. Zero out the negative |\medmuskip| in script styles. @732
* 29 May 1978
S275. Be prepared to handle an undefined control sequence during \\{get_x_token}.
	(Can fix this by brute force, using \\{get_token} instead of \\{get_next}.)
	@380
D276. Correct the superscript shift when a single character is raised. @758
R277\>184. Mask off all but 7 bits in |\char| routine,
	to avoid space-factor index out of range. @435
# More memory capacity overflows.
E278\>22. Fix \TeX's overflow stop so that I don't have to wait for loading of the
	|BAIL| debug routines. [System dependent.] @93
F279. Remember to adjust the page number
	when a file page ends in mid-macro. [System dependent.] @306
* 5 Jun 1978
R280. Make sure that the arguments of positioning commands don't overflow
	their field size. @610
I281. Report the excess amount when giving an overfull box warning. @666,677
* 7 Jun 1978
Q282. Use $\ge$ instead of $>$ as termination criterion in \\{var_delimiter}. @714
R283. Disallow |\eject| in math mode. [In \TeX78, |\eject| is
	distinct from |\break|; in horizontal mode it includes
	\TeX82's `|\vadjust{\break}|'.] @1102
Q284. Don't put too much clearance above |\sqrt| in text style. @737
* 9 Jun 1978
G285\>110. Make \\{align_state} an integer variable, not \\{boolean},
	so that |\eqalign| can be within another |\eqalign|. @309
C286. A |\mark| should expand its input. @1101
* 10 Jun 1978
E287. Provide for preloading of fonts. @1320
L288. Close the output file before switching to edit the input file with
	the `|e|' option. @84
E289. Return adjustments found by \\{hpack} to free storage if
	they're not used. [Later, \\{hpack} will detach them only
	when they're used.] @655
Q290. Strive for consistency between \\{make_under} and \\{make_over}.
	@735
* 18 Jun 1978
B291\>236. Fix a serious error in \\{rebox}
	(`$b$' instead of `$\\{list_ptr}(b)$'). @715
# Strange that such a bug would now surface for the first time!
C292. Remove |\deg| from |INITEX|, since macros suffice.
Q293. Add an extra hyphenation penalty for two hyphenated lines in a row. @859
* 19 Jun 1978
S294. Introduce the `\\{no_new_control_sequence}' switch. Among other things,
	this will prevent an undefined control sequence following \\{scan_math}
	from clobbering the save stack. @259
* 20 Jun 1978
L295. Change the badness test
	`$\\{glue}\le0.0$' to `$\\{glue}\le0.0001$'. [\TeX82 will avoid such
	problems by calculating badness without floating point arithmetic.] @99
R296. Force \\{badness} to be at most $10^{19}$. @108
I297. Add \\{end_template} for better error recovery in alignments. @375
E298\>287. Make |INITEX| more like the real \TeX; my simple scheme for
	font preloading was no good because it left thousands of `dead'
	words in memory. @8
E299. Economize disk space by using internal arrays in load
	modules that aren't being reinitialized. [System dependent.]
E300. Move the declaration of \\{mem} to the semantics module, so that the
	object code will be more efficient. [System dependent. The code of
	\TeX78 was divided into separately compiled modules for syntax,
	semantics, output, extensions, and general organization.]
* 21 Jun 1978
# Today I'm working on the user manual.
C301. Disallow |\input| except in vertical mode. [I will change this in
	\TeX82, treating |\input| as a case of expansion.] @378
I302. Add error recovery for \\{endv} and \\{par_end} occurring in math mode.
	@1047
G303. Generalize |\ifT| to |\if T|. @506
* 22 Jun 1978
F304. Preload the |\bullet| [later done by |plain.tex|].
D305\>256. Get the correct \\{prev_depth} at the beginning of an alignment. @775
C306. Change |\eject| so that it ejects only once. @1000
* 14 Jul 1978
I307. Look in standard area if a file isn't found in the user's area. @537
I308. Echo all online inputs in the transcript file. @71
* 19 Jul 1978
Q309. Equalize spacing when only one of numerator/denominator is big. @745
Q310. Prevent subscript from getting too high above baseline. @757
R311. Avoid infinite loop when stack overflows: \\{push_input} should say
	`{\bf if} $\\{input_ptr}\ge\\{stack_size}\;\land\;\\{interaction}=
	\\{error_stop_mode}$'. @321
* 22 Jul 1978
C312. Make |\quad| meaningful outside math mode. (All fonts must
	be generated again!) @558
I313. Show the nesting level at the end of \\{show_activities}.
	[But I decided not to do this in \TeX82.] @218
C314. Put in |\>| [namely, |\mskip\medmuskip|;
	\TeX78 already has |\|{\tentex\char'35}, for conditional |\thinmuskip|,
	as well as the negative amounts |\<|,~|\|{\tentex\char'34}].
	Change the name of vector accent from |\>| to |\b|. [Math spacing
	operators will become much more general in \TeX82.] @716
* 25 Jul 1978
Q315\>94. Give the correct |\hsize| and |\vsize| to the null boxes created
	at |\end|. @1054
A316\>94. And don't ``append'' them. [Later this was changed, so
	that it would work better with generalized output routines.] @1054
I317\>297. Remove the control sequence |\endv|,
	since error recovery is now better. @375
I318. Define another mode of tracing: It says `|OK|' and stops after
	|\showlists|. @1298
Q319\>244. Give better defaults to parameters. [Later done by |plain.tex|.] @209
I320. Allow more bits in the packed representation of\/ |\showboxdepth|. @238
I321. Scan past delimiters and/or dimensions when recovering from
	ambiguous fractions. @1183
R322. Reduce accent numbers modulo 128 or 512, depending on the
	mode. @1165
I323. Include a warning, `|(\end occurred on level ...)|'. @1335
* 28 Jul 1978
# (I'm writing Chapter 27 of the manual: `Recovery From Errors'.)
I324. Improve the error message in \\{scan_digit}. [This procedure will change
	its name to \\{scan_eight_bit_int}, when the number of registers
	increases from 10 to~256.] @433
I325. Don't report overfull boxes if they're less than .1~point
	over. @666,677
I326. Give the user extra chances to define the font, if \\{read_font_info}
	is unsuccessful. @560
I327. Change default recovery for bad parameter number from |#1| to |##|, since
	|#1| won't always work and since |##| is probably intended. @479
I328. Omit the |"Negative?"| message on things like \\{scan_char_num}. @435
I329. Improve error recovery when a large delimiter isn't in family~3.
	[Obsolete.]
I330. Give a more appropriate error message when the input is `|$\right|'. @1192
# Currently \TeX\ says `|Missing $|'!
I331. Call \\{back_input} before the error message in \\{back_error},
	not afterwards. @327
* 1 Aug 1978
I332. Give an appropriate warning when there's no input file and the user
	types `|e|'. @84
L333. Increase the system pushdownlist size so that the manual will compile.
	[Procedures \\{hlist_out} and \\{vlist_out} can recurse deeply.]
# Yesterday I distributed 45 preliminary copies of the manual; today I
	took out the ``debugging hooks'' and put \TeX\ up as a system program.
* 2 Aug 1978
# I'm typing Volume 2 again (currently in Section 4.2.2). Culture shock!
G334. Introduce a |\ragged| parameter, to indicate a degree of raggedness.
	[Previously, ragged-right setting was performed when the
	|\tolerance|/100 was odd! Eventually a better approach,
	with |\rightskip| and such things, will be discovered.] @886
Q335. Omit the `widow penalty' in one-line paragraphs. @890
* 5 Aug 1978
G336. Generalize |\pageno| to |\count|\<digit>. @236
D337\>285. Update \\{align_state} when recovering from `|Missing {|' and
	`|Extra }|' errors. @1069,1127
I338. Show ``runaway'' tokens, making it easier to pinpoint an error. @306
* 22 Aug 1978
G339. Add |\predisplaypenalty|. @1203
I340. Clarify error messages; they should indicate when something has been
	inserted, etc. @1064
* 23 Aug 1978
I341\>114. Substitute `|Extra }|' for the losing `|Missing \cr|' error message. @1069
I342\>213. Go past online insertions in \\{show_context}. @311
Q343. Exact no penalty for breaking one line before a display. @1145
I344\>338. Check for runaways at end of file. @362
I345. Give error message when a macro argument begins with |}|. @395
* 24 Aug 1978
L346\>213. Remove extra line-feed in \\{show_context} after printing insertions.
	[System dependent.] @318
* 25 Aug 1978
Q347. Leave no glue at top of page, even after |\eject|. @997
* 27 Aug 1978
P348. Adopt Guy Steele's new version of the \TeX\ source files. [He has
	recently made a copy and modified it by introducing
	compile-time switches for MIT conventions as an alternative to SUAI.
	This is the first time that \TeX\ is being ported to another site;
	additional switches for PARC, TENEX, TOPS10, and TOPS20 will be
	added later, using the Steele style.]
* 1 Sep 1978
Q349. Don't pass over leader nodes in the \\{try_break} background
	computation. [At this time, leaders have not yet been
	unified with glue.] @837
Q350\>82. Prune away all penalties at the top of a page. @997
* 4 Sep 1978
I351\>338. Include `|\|' in error message about a runaway argument. @306
* 8 Sep 1978
# I just remade all the fonts, with increased ligature field size.
B352\>350. Insert a necessary {\bf goto} statement in the first branch of
	the new penalty routine within \\{build_page}. @997
* 30 Sep 1978
M353\>338. Make the token list for runaway arguments meaningful outside
	of \\{macro_call}. (I just had a runaway argument ending with
	`|\lcm|', which turned out to be the
	control sequence in hashtable location 0.) @371
R354. Avoid infinite loop when recovering from |$$| in
	restricted horizontal mode. @1138
L355. Fix two hyphenation bugs related to |-ages|, |-ers|.
	[A completely new algorithm for hyphenation will go into \TeX82.]
Q356. Add |-est| to hyphenation routine;
	also disable |puz-zled| and |rat-tled|, etc.
* 4 Oct 1978
G357. Add new primitive |\vtop|. @1087
Q358. Treat implicit kerns properly after discretionary hyphens have been
	inserted. @914
* 4 Nov 1978
Q359. Forget the half quad originally required at left and right when
	centering displayed equations without equation numbers. @1202
* 11 Nov 1978
R360. Don't let the postamble come out empty. [This could occur if no fonts were
	selected.] @642
* 15 Nov 1978
C361. Allow optional space after digit in \\{scan_int} routine. @444
* 17 Nov 1978
R362. Make the \\{check_mem} procedure slightly more robust. @167
* 20 Nov 1978
C363. Make the |\par| in a |\def| match the |\par| that comes automatically with
	a blank line. (Suggested by Terry Winograd.) @351
G364. Add new parameter |\mathsurround| for spacing before and after
	math in text. @1196
G365. Extend |\advance| to allow increase by other than unity. [At this
	time it applies only to the ten |\count| registers, and it is
	called |\advcount|.] @1238
* 25 Nov 1978
G366. Add a new primitive: |\unskip|. @1105
G367. Add new primitives |\uppercase| and |\lowercase|. @1288
* 28 Nov 1978
M368\>338. Don't let |\mark| and \\{macro_call} interfere with each other's
	\\{scanner_status}. @306
M369. Omit extra |}| after \\{show_node_list} shows a |\mark|,
	since the right brace is already there. (See \#210.) @176
G370. Add a new primitive suggested by Terry Winograd: |\xdef|. @1218
* 29 Nov 1978
S371. Delete a space following |\else{...}| also in the
	false case. [\TeX78 uses braces, not |\fi|, for conditionals.]
D372\>320. Make |\tracing| set |\showboxbreadth| as advertised. @198
F373. Account properly for kerns in width calculations of \\{line_break}.
	@866
Q374\>364. Delete a \\{math_node} at the beginning of a line. @148
A375\>339. Guarantee that |\predisplaypenalty=10000| will suppress page breaking
	before a display. @1005
* 6 Dec 1978
L376. Change the file opening statement to allow lines up to 150 characters long.
	[System dependent.]
* 16 Jan 1979
F377\>365. Initialize \\{negative} properly in the |\advance| routine
	with a |\count| as argument. @440
* 20 Jan 1979
R378. Try to keep complex, buggy preambles of alignments from
	crashing the program. @789
* 17 Feb 1979
I379\>376. Give more detailed information when warning about a
	long line being broken. [System dependent;
	the buffer size in \TeX78 is very limited.]
L380. Declare $p$ local to \\{try_break}, for the ``rare'' case code.
	[My original program included the following comment:
	``This case can arise only in weird circumstances due to
	changing line lengths, and the code may in fact never be executed.''
	Later Michael Plass will discover that variable line lengths require an
	entirely different algorithm, using \\{last_special_line}.]
	@847
F381\>334. Don't omit the raggedness correction when the
	last line of paragraph has to shrink. [Obsolete in \TeX82.]
* 22 Feb 1979
F382\>363. Don't forget to return from \\{get_x_token} after finding |\par|. @351
Q383. Add a new parameter: |\lineskiplimit|. @679
C384. Change the syntactic sugar:
	`|\hbox par|' replaces `|\hjust to ...{overfull}|'. [This vastly improves on
	the old idea (see \#40), but there still is no internal vertical mode.]
C385. Introduce new names |\hbox| and |\vbox| for |\hjust| and |\vjust|. @1071
G386. Add a new condition: |\ifpos|. [It will later be
	generalized to |\ifnum| and |\ifdim|.] @513
G387. Add |vu| and |\varunit|. [\TeX82 will eventually allow arbitrary
	internal dimensions as units of measure.] @453
G388\>312. Add an |em| unit. @455
C389. Legalize |\hbox spread |\<negative dimension> [since \\{scan_spec}
	no longer uses the sign as a flag]. @645
* 10 Mar 1979
C390\>370. Make \\{scan_toks} expand |\count| during |\xdef|. [This will
	change later when |\the| and |\number| are introduced.] @367
* 23 Mar 1979
Q391. Put only 100000\thinspace pt stretch at the end of a paragraph instead of
	10000000000\thinspace pt.
	[In \TeX78, ``infinite'' glue is actually finite but large; in the
	language of \TeX82 we would say that |\parfillskip|, which is
	not yet user-settable, is being changed to be like |\hfil| instead of
	like |\hfill|.] @816
Q392. Treat the last line of a paragraph more consistently with
	the other lines (e.g., when |\hfil| appears in mid-paragraph), by
	effectively inserting \\{inf_penalty} at the end. @816
* 31 Mar 1979
S393. Ensure that penalty nodes aren't wiped out, in weird cases where
	breaks occur at penalties that normally disappear. @879
* 27 Apr 1979
A394. Correct the page number count when files begin with an empty page.
	[System dependent.]
G395. Allow the \\{math_code} table to be changeable via |\chcode|.
	[In \TeX82, |\chcode| will split into |\mathcode| and |\catcode|.] @1232
I396\>332. Don't accept `|e|' after an error message if not
	inputting from a file. @84
* 29 May 1979
F397. Don't call \\{end_file_reading} if you haven't already invoked
	\\{begin_file_reading}; this could happen when trying to
	recover from an error in \\{start_input}.@537
* 7 Jun 1979
A398\>306. Be sure to eject two pages,
	when |\eject| comes just at the time another break is preferable
	(e.g., when the page has just become too full). @1005
* 27 Jun 1979
I399\>354. Don't say `|You can't do that in math mode|' when the user
	says `|$$|' in restricted horizontal mode! @1138
* 30 Jun 1979
G400. Add |wd|, |dp|, |ht| dimension units. @455
I401\>307. Don't try the system area for file names whose area is explicitly
	indicated. @537
* 1 Jul 1979
G402. Allow letters as (ASCII) numbers [without the |`| marker introduced
	later]. @442
* 2 Jul 1979
F403. Fix a |\gdef| bug: If the control sequence was never defined before
	[this later became the \\{restore_zero} option],
	don't remove it at group end. @282
* 16 Jul 1979
I404\>320. Update \\{show_noad_list} to be like \\{show_node_list}.
	[The two routines, originally separate, will be merged in \TeX82.] @238
* 18 Jul 1979
G405. Extend capacity from 32 fonts to 64 fonts if desired. @134
Q406. Add new \\{extra_space} parameter to all text fonts (requested
	by Frances Yao). @558
F407. Make each \\{node_noad} print properly in \\{show_noad_list}. @183
Q408. Make |\jpar| allow any break if it is 1000000 or more.
	[In \TeX82, a |\tolerance| of 10000 or more allows any break.] @851
* 23 Jul 1979
E409. Introduce new primitives |\hfil|, |\vfil|, |\hfilneg|, |\vfilneg|. @1058
G410. Add |\ifmmode|. @501
G411. Add |\firstmark|. @1012,1016
C412. Allow break at leaders (horizontal mode only). @149
* 25 Jul 1979
I413\>213. Revise \\{error} so that online insertions work properly
	after end-of-file errors. @336
B414\>411. Change `{\bf if} $\\{first_mark}\ne0$' to
	`{\bf if} $\\{first_mark}\ge0$' [because $-1$
	is used to indicate `not yet given a value']. @1012
* 28 Jul 1979
C415\>370. Stop |\xdef| from expanding control sequences after |\def|'s.
	[This decision will be rescinded later, after several more years of
	experience with macro expansion will suggest better ways to cure
	the problem.] @366
I416. Change symbolic printout for control symbols. [System dependent.] @49
L417\>308. Avoid linefeeds in the transcript file. [System dependent.]
C418\>370. Expand |\topmark|, etc., in |\xdef|. @366
* 4 Aug 1979
B419\>413. Fix an error introduced recently: |\par| was suddenly
	omitted at end of page. [System dependent.]
* 11 Aug 1979
P420. Change error messages that use |SAIL| characters not in
	standard ASCII. @360
* 28 Aug 1979
D421\>411. Move the command `$\\{first_mark}\gets-1$' from \\{vpackage}
	to \\{fire_up}. @1012
S422\>403. Correct a serious |\gdef| bug:
	Control sequences don't obey a last-in-first-out
	discipline, so \TeX\ loses things from the hash table when deleting a
	control sequence. @259
# To fix this, I either need to restrict \TeX\ (so that
	|\gdef| can be used inside a group only for control sequences already
	defined on the outer level) or need to change the hash table algorithm.
	Although all applications of \TeX\ known to me will agree to the
	former restriction, I've chosen the latter alternative, because it gives me
	a chance to improve the language: Control sequences
	of arbitrary length will now be recognized.
D423. Make sure that \\{unsave} cannot call \\{eq_destroy}
	with a value from the upper part of \\{eqtb}. @282
# I noticed this long-standing bug while fixing \#422. It had very
	low probability of causing damage (e.g., it required a certain field
	of a floating-point number to have a certain value), but it would have
	been devastating on the day it first showed up!
* 29 Aug 1979
F424. Call \\{eq_destroy} when a control sequence is |\gdef|'ed
	after being |\def|'ed. @283
F425\>418. Treat the first token consistently
	when |\topmark| and its cousins are expanded in \\{scan_toks}. @477
# Now I've checked things pretty carefully and I think \TeX\ is ``fully debugged.''
* 25 Jan 1980
I426\>338. Display runaway alignment preambles. @306
G427. Introduce active characters (one-stroke control sequences).
	[I don't yet go
	all the way: The meanings of `|x|' and `|\x|' have to be identical.] @344
* 7 Feb 1980
F428\>314. Fix a glaring omission: Op space |\>| was
	never implemented in math mode! @716
* 25 Feb 1980
G429. Add a new dimension `|ex|' (for units of xheight). @455
* 3 Mar 1980
C430\>427. Allow the control sequence |\:| to be redefined
	[it was the `select font' operator];
	this allows the character |:| to be active. [Obsolete.]
* 23 Mar 1980
# An extend-\TeX-for-the-eighties party:
G431. Add a new |\copy| feature. @204
G432. Add a new |\unbox| feature. @1110
G433. Add a new |\open| feature [later |\openout|]. @1351
G434. Add a new |\send| feature [later |\write|]. @1352
G435. Add a new |\leqno| feature, requested by MDS. @1204
G436. Add a new |\ifdimen| feature [later |\ifdim|]. @513
C437. Make |\|\<space> in vertical mode begin a paragraph. @1090
G438. Add a new |\font| feature [replacing the silly previous convention that
	a font must be defined when it is first selected]. @1256
G439. Add new |\parval| and |\codeval| features [later
	|\the|\thinspace\<whatever>\thinspace]. @413
C440\>427. Don't let active characters gobble the following space. @344
G441\>208. Add a new parameter to govern amount of token list dumped. [Obsolete.] @295
G442. Add a new |\linebreak| feature [later replaced by |\break|]. @831
* 25 Mar 1980
# (Still working on the above, also thought of more.)
G443. Add a new |\mskip| feature. @716
G444. Add a new |\newname| feature (soon changed to |\let|). @1221
G445\>430. Allow any control sequence to be redefined. @275
I446. Send the output to the user's current file area, even when
	input comes from elsewhere. @532
* 27 Mar 1980
Q447. Compute the xheight for accents in math mode from
	family~1, not family~3. [Obsolete.]
* 28 Mar 1980
Q448. Increase minimum clearance between subscript and superscript. @759
* 29 Mar 1980
Q449\>222. When a display follows a display, the second should have the
	`shortskip' glue. @1146
* 4 Apr 1980
A450\>445. Look at current token meanings when trying to recognize
	|\tabskip| in alignment preambles. @782
* 23 Apr 1980
I451. Estimate the length of printed output, for the new
	priority feature on our XGP device driver. [System dependent.]
C452\>434. Break long |\send| lines
	into pieces so that the file can be read in again. [System dependent.]
* 19 May 1980
Q453\>182. Don't make |\left| and |\right| delimiters too large; they
	need to be only 90\% of the enclosed size. [This eventually
	became |\delimiterfactor|.] @762
* 21 May 1980
G454. Add a new |\pagebreak| feature [later |\vadjust{\break}|]. @655
* 13 Jun 1980
# Today I'm beginning to overhaul the line-breaking routine,
	and I'll also install miscellaneous goodies.
G455. Allow a radical sign to be in different font positions. @737
E456. Clear empty tokenlists off input stacks to allow deeper recursions
	(suggested by Jim Boyce's macros for chess positions). @325
G457. Make |\spaceskip| and |\parfillskip| changeable. @1228
G458. Add a new parameter |\rfudge| (per request of Zippel) [later |\mag|]. @288
G459. Add a new parameter |\loose| [later |\looseness|];
	now parameters are allowed to take negative values. @875
E460. Remove the variable \\{just_par}. [Obsolete; it was the \\{real} equivalent
	of an \\{integer}].
* 14 Jun 1980
Q461. Install new line-breaking routines, including |\parshape|.
	(These major changes are introduced as Michael Plass
	and I write our article.) @813
G462. Add a new parameter |\exhyf| [later |\exhyphenpenalty|]. @869
* 16 Jun 1980
S463\>444. Change conventions in \\{eqtb} so that glue is distinguishable
	from other equivalents. @275
A464\>444. Don't expand |\b| in |\xdef{\d\b{...}}| after |\let\d=\def|.
	[Obsolete.]
D465\>444. Avoid creating dead storage when doing \\{unsave} in certain regions. @275
* 17 Jun 1980
C466. Allow negative dimensions in rules. @138
* 19 Jun 1980
B467\>463. Make the new test for glue at the outer level of \\{show_eqtb}. @252
* 27 Jun 1980
Q468\>453. Don't let |\left| and |\right| become too small for big matrices.
	[This eventually became |\delimitershortfall|.] @762
* 3 Aug 1980
Q469. Don't move extra-wide, numbered equations flush left unless
	they begin with glue. @1202
* 15 Sep 1980
M470\>461. Say `$\ge\\{fz}$' instead of `$>\\{fz}$' in the pre-hyphenation
	routine; I'd forgotten my definition of \\{fz} [a variable used to test
	for a sequence of lowercase letters in the same font]. @897
R471\>395. Check the range of the index in |\chcode| before saving the old value.
	@1232
* 18 Sep 1980
D472\>457. Don't forget to increase the reference count to |\parfillskip|,
	or it will mysteriously vanish. @816
* 19 Sep 1980
C473\>412. Make leaders break like glue in both horizontal and vertical modes.
	@149
Q474\>364. Make |\mathsurround| break properly at left and right end of lines.
	@879
* 13 Oct 1980
I475\>461. Remove spurious overfull boxes generated when the looseness criterion
	fails. [Obsolete.]
A476\>461. Redesign the iteration for looseness; breakpoints were not chosen
	optimally. @875
E477\>461. Avoid storing a lot of breakpoints when they are dominated by
	others. @836
B478\>366. Don't say `\\{cur_node}' when you mean `\\{mem}[\\{cur_node}]'. @1105
Q479\>461. Prefer the oldest break to the youngest break
	when two break nodes have the same total demerits. @836
L480\>461. Don't make badness too big for floating-point calculations,
	when forced to make an overfull box. [Obsolete.]
* 10 Dec 1980
R481. Make it impossible to get unmatched `|}|' in a delimited macro
	argument. @392
G482. Add new |\topsep| and |\botsep| features. [These are \TeX78's
	way to put space at the edge of inserts,
	replaced in \TeX82 by the |\skip| register corresponding
	to an |\insert| class.] @1009
* 6 Jan 1981
P483. Install new routines for reading the font metrics, using Ramshaw's
	|TFM| files instead of\/ |TFX| files. @539
I484. Abort after reporting 100 errors, if not pausing on errors. @82
G485. Add new |\spacefactor| and |\specskip| and |\skip| primitives.
	[At this time we write `|\specskip3=10pt|' and `|\skip3|' for what
	will become `|\skip3=10pt|' and `|\hskip\skip3|' in \TeX82.] @1060
G486\>366. |\unskip| is now allowed in internal vertical mode. @1105
* 26 Jan 1981
B487\>482. Don't say `\\{mem}[$q$]' when you mean `$q$'. (See \#143 and \#478.) @1009
* 27 Feb 1981
I488\>417. Put some linefeeds back into the transcript file, in order
	to prevent overprinting in listings. [System dependent.]
G489. Add a new |\dpenalty| feature [later |\postdisplaypenalty|]. @1205
G490. Add the dimension |cc| for European users. @458
C491. Make \\{scan_keyword} match uppercase letters as alternatives
	to lowercase ones (suggested by Barbara Beeton's experiments
	with |\uppercase|). @407
I492. Add nonstop mode so that overnight batch processing is possible. @73
* 2 Mar 1981
S493\>422. Fix a still more serious |\gdef| bug: The generality
	of\/ |\gdef| almost makes it a crime to
	forget {\sl any\/} control sequence names, ever! (The previous bug was
	only the tip of an iceberg.) @259
I494. Issue warning message at the end of a file page if nesting level isn't zero.
	[System dependent.]
* 5 Mar 1981
I495. Keep track of maximum memory usage, for statistical
	reporting. [Obsolete.] @125
Q496\>350. Prune away glue and penalties at top of page after marks, sends,
	inserts. @1000
G497. Allow |\mark| in horizontal mode. [Later it will
	be |\vadjust{\mark...}|.] @655
C498. Allow optional space before a required left brace, e.g., |\if AA {...}|.
	[See \#251.] @403
I499. Issue an incomplete |\if| error, to help catch a bad |\if|. @336
* 17 Mar 1981
I500\>494. Omit the warning message at end of a file page unless
	the nesting level has changed on that page. [System dependent.]
Q501\>310. Fix the spacing when there is a very tall subscript with
	a superscript. @759
* 20 Mar 1981
S502\>371. Make space-eating after |\else| fully consistent between the
	true and false cases. [Obsolete.]
* 24 Mar 1981
B503\>496. Change \\{glue_spec_size} to \\{ins_spec_size}
	in \\{vpackage} [where insertions are done]. [Obsolete.]
* 5 Apr 1981
B504\>501. Fix a typo (`|+|' instead of `|-|') in the new subscript code;
	this shifted certain subscripts down instead of up. @759
* 18 Apr 1981
G505. Make leaders with rules of specified size act like variable rules.
	@626,635
* 29 Apr 1981
A506\>461. Don't consider $\\{badness}>\\{threshold}$ at a line |\break|
	except in an emergency. @854
* 13 Jul 1981
C507\>402. Allow other characters as numbers. @442
R508\>294. Avoid dead storage if a \\{no_new_control_sequence} error occurs.
	[Obsolete.] @259
G509. Add a new |\ifx| feature. @507
G510. Add new features |\xleaders| and |\cleaders|. @626,635
* 14 Jul 1981
S511\>507. Amend the new code for constants;
	the `|.|' in `|.5|' is thought to mean \O{056}! @442
L512\>507. And fix an egregious blunder in that code: New commands at the
	end of a procedure are ignored when earlier statements
	exit via {\bf return}. @442
* 4 Aug 1981
P513. Accept alphabetic codes for all online error recovery options,
	instead of insisting on control codes like line feed or form feed.
	[The original error-recovery codes were suggested by the
	conventions of the |SAIL| compiler.] @84
G514. Add a new |\thebox| feature [later |\lastbox|]. @1079
* 7 Aug 1981
G515. Add |fil|, |fill|, and |filll| as units for glue stretching
	or shrinking. @454
I516. Suppress the overfull box error when shrinkage amount is negative. @664
* 9 Aug 1981
Q517. Let unset boxes inherit the size of their parent in alignments. @810
* 12 Apr 1982
F518. Make |INITEX| dump out the \\{font_dsize} array needed by
	the new |DVI| output module. @1322
* 1 May 1982
S519\>151. Fix \\{clean_box} so that \\{mlist_to_hlist} cannot make
	$\\{link}(q)=0$ and $\\{type}(q)=\\{glue_node}$. @720
# [That was the historic final change to \TeX78. All subsequent entries
	in this log refer to \TeX82.]
* 15 Jul 1982
# Finished draft of test program and began debugging about 1430
	[2:30\thinspace pm]. Taking my time.
BX1. Change \\{eqtb}[\\{cur_font}] to \\{eqtb}[\\{cur_font_loc}]. @232
# Not logging changes to the exposition.
# Compile time is about 2 minutes CPU, times 5 for time-sharing;
	add another half minute for linking and loading.
# Hash table and \\{get_next} seem to be working, with no changes needed!
# Time out 1630--1815 for Jill's birthday party.
LX2. Insert {\bf begin} \dots~{\bf end} around \\{dump_int} macro. @1305
IX3. Print two blank spaces before date in \\{open_log_file}. @536
AX4. Update $x$ and \\{var_used} outside the {\bf for} loop. @1311
BX5. Change {\bf if} $=$ to {\bf if} $\ne$ as loop exit condition. @1315,1316
# The |TRIP| test should preload more fonts.
LX6. Insert {\bf begin} \dots~{\bf end} around statistics output. @1334
FX7. Must \\{get_x_token} when scanning a number. @445
IX8. Interactive \\{debug_help} needs to print a newline. @1338
FX9. Include \\{ignore_spaces} and \\{math_accent} in \\{print_cmd_char} cases. @266
IX10. Don't call \\{confusion} when \\{print_cmd_char} sees unknown code. @298
# Compiler bug causes stack overflow. Retiring for the night at 2145.
* 16 Jul 1982
# Starting at 0700; DRF has fixed the compiler.
RX11. Allow arbitrary integer parameters in diagnostic print routines. @237,699
TX12. Say \\{cur_tok}, not \\{cur_val}, when you mean \\{cur_tok}. @440
FX13. Make |\pause| effective also on first line of a file. @538
FX14. Show context after online deletion. @88
IX15. Bypass reference count when \\{debug_help} shows a token list. @1339
BX16. Change `{\bf case} $p$' to `{\bf case} \\{type}($p$)'. @1000
FX17. Fix timing of \\{print_ln} when scrolling help messages. @90
PX18. Make \\{other_char} the default category for ASCII control codes too. @232
AX19. Use special scanning method for font number in \\{new_font}. @1257
# Eating lunch, 1020--1035, while the machine slowly recompiles everything.
FX20. Don't forget to increase $k$ in the {\bf while} loop. @355
DX21. Adjust \\{limit} properly after line changed when pausing. @363
FX22. Remember to return a value in \\{new_spec} and \\{new_penalty}. @151,158
# Now stepping through \\{line_break} in simple case.
AX23. Don't prune unwanted nodes if $\\{cur_p}=\\{null}$. @877
FX24. Print a closing parenthesis when displaying glue nodes. @189
SX25. Use \\{last}, not \\{limit}, in \\{term_input}; else error prompt causes
	trouble when $\\{state}=\\{token_list}$. @71,87
DX26. Set $\\{first}\gets\\{limit}+1$ after \\{init_terminal}. @331
DX27. Make sure \\{set_trick_count} is always performed. @317
* 17 Jul 1982
IX28. Add new diagnostic feature |\tracingcommands|. @299,1031
# Debugging of system-dependent code not shown in this log.
# Tangling \TeX\ now takes 1.75 minutes; about 75K bytes, 108K tokens.
# Redundant semicolon sends Pascal compiler into infinite loop!
FX29. Initialize $\\{passive}\gets\\{null}$. @864
AX30. Fix pseudoprinting when the line is empty. @318
EX31. Merge adjacent free areas of dynamic memory before dumping. @131
FX32. Print the word |mode| in \\{print_mode}. @211
IX33. Improve message and help in case of weird error. @415
GX34. Allow optional space after |\def| and similar constructions. @473
MX35. Declare \\{alpha} to be integer in \\{read_font_info}. @560
AX36. Fix timing of \\{back_input} in \\{scan_dimen}. @448
IX37. Back up after missing number error. @446
IX38. Show the `|at|' size that is considered improper. @1259
IX39. Streamline the dialog in \\{debug_help}. @1338
MX40. Take output of \\{the_toks} from the advertised place. @467,1297
TX41. Say \\{trie_fix}($q$), not \\{trie_fix}($p$). @959
SX42. Decrease low limit of \\{error_count} to $-1$. @76
* 18 Jul 1982
FX43. Clear initial reference count of macro definitions. @473
AX44. Fix timing of \\{back_input} in \\{scan_glue}. @461
BX45. Use \\{cur_val_level}, not \\{cur_val}, when checking levels. @461
BX46. Multiply |fil| units by $2^{16}$ for correct scaling. @454
BX47. Don't confuse \\{glue_base} with \\{skip_base}. @1237
AX48. Fix \\{print_scaled} so that 0.01 doesn't come out |0.1|. @103
IX49\>X28. Show mode changes when tracing commands. @299
LX50. Don't say {\bf if} $(n=0)\lor(\,\ldots\;\hbox{\bf div}\;n)$ in Pascal. @105
BX51. Don't confuse \\{box_flag} with \\{box_code}. @1075
SX52. Reset \\{offset} on \\{print_ln} even in \\{no_print} mode. @57
SX53. Fix restarting of interrupts after \\{big_switch}. @1031
LX54. Don't loop {\bf for} $k\gets a$ {\bf to} $b-1$ when $b=0$ if $k$ is
	declared nonnegative.
IX55. Put `|=|' sign into the \\{format_ident}. @1328
SX56. Allow $r$ to be any integer in \\{get_node}. @125
IX57. Don't put the output of \\{print_file_name} in quotes. @518
IX58. Say `|dumped|' after dumping. @1311
EX59. Eliminate unnecessary initialization code. @1332
LX60. Get the file reading started right when beginning to undump. @1308
IX61. Give forlorn message if format file can't be loaded. @1303
FX62. Assign value to \\{cur_val} after glue arithmetic. @1239,1240
* 19 Jul 1982
LX63. Don't say {\bf if} $p>\\{max}\lor\\{free}[p]$ in Pascal. @169
AX64. Fix memory-undump logic; loops are out of phase with input. @1312
BX65. Undump \\{hyph_word}[$j$], not \\{hyph_word}[$k$]. @1325
# At last |trip.fmt| loads without bombing out.
PX66. Remove assignment of array to array, not allowed by IBM Pascal
	(Susan Plass). @167
PX67. Simplify an expression that's too big for IBM Pascal (Susan Plass). @1009
AX68. Go to \\{contribute}, not \\{done}, after insertions. @1000
IX69. Decrease \\{depth_threshold} if there's not enough string space. @198
IX70. Show rules as `{\tt\char`\|}' in short displays. @175
IX71. Don't show null glue in short displays. @175
SX72. Set $\\{job_name}\gets0$ as part of output initialization. @528
SX73. Don't complain of infinite shrinkage on |0pt minus 0fil|. @825,976,1009
IX74. Use different prompt at beginning when accepting a file name. @37
FX75. Reset \\{last_glue} on nonglue nodes. @996
BX76. Remember to call \\{error} after printing |OK|. @1293
LX77. Insert {\bf begin} \dots{ \bf end} around program text of section. @1025
FX78. Define the |\shipout| primitive. @1071,1073
AX79. Introduce \\{write_loc} analogous to \\{par_loc}. @1344,1371
FX80. Dump and undump \\{par_loc} and \\{write_loc}. @1313,1314
FX81. Allow \\{the} in \\{scan_the} [later \\{scan_something_internal}]. @413
EX82. Interchange command codes $\\{the}:=:\\{number}$ [later \\{convert}]. @210
BX83. Don't confuse \\{breadth} with \\{depth}. @236
IX84. Add string printing feature to \\{debug_help}. @1339
FX85. Set $\\{state}\gets\\{mid_line}$ in \\{begin_file_reading}. @328
# Time out 2105--2200 to pick up Jenny from driving lesson.
LX86. Keep $c\le127$ when deleting 99 tokens. @88
SX87. Don't check for \\{str_room} error when $\\{selector}=\\{new_string}$. @1328
* 21 Jul 1982
IX88. Gather more statistics: String usage, font info, hyphen exceptions, stacks. @1334
DX89\>X79. Initialize \\{write_loc} from \\{cur_val}, not from \\{cs_ptr}. @1344
FX90. Remember to pack file name for |\open|. @1374
SX91\>X34. Defuse |\outer| test before scanning optional space after `|}|'. @473
SX92. Don't allow \\{prepare_mag} to cause errors after \\{jump_out}. @84
# The first page of |DVI| output is {\sl perfect\/}! Pause to play piano.
BX93. Don't confuse \\{dimen_base} with \\{scaled_base}. @1237
DX94. Initialize $\\{link}(\\{page_head})\gets\\{null}$ when beginning a page. @991
SX95. Correct \\{cur_height} more often, since \\{max_depth} might be negative. @972,973
AX96. Calculate page dimensions properly after vertical kerns. @973
SX97. Install new \\{page_contents} logic to handle interaction between
	insertions and |\topskip|. @987,1008
SX98. Allow \\{top_skip} glue to be a valid breakpoint. @1001
FX99. Don't forget to count \\{dyn_used} in inner loop [erroneous analysis
	retracted later]. @1034
FX100. Set $p\gets q$ after migration step. @655
FX101. Clear \\{prev_graf} to zero at start of paragraph. @1091
LX102. Put parens into negated \\{leader_flag} macro. @1078
# Time out 1720--1920 for John's birthday dinner.
DX103. Scale \\{best_height} when adjusting \\{page_goal}. @1010
AX104. Simplify logic of split insertions; three states become two. @981,1019,1020
MX105. Don't omit first character when showing a macro argument. @400
RX106. Prevent clobberage if macros have too many parameters. @390
* 22 Jul 1982
IX107. Tell how many |DVI| bytes were output. @642
IX108\>X88. Adjust for singular or plural statistics. @1320,1334
SX109\>X98. Consider \\{page_head} a glue node, to inhibit unwanted break. @988
DX110. Introduce \\{new_skip_param} to keep reference counts updated. @679,969,1001
DX111. Record the correct size of new insertion after it's split. @1010
DX112. Use \\{free_node}, not \\{flush_node_list}, when recycling insertion
	nodes. @1022
SX113. Make online insertions work after \\{get_next} is interrupted. @87,324,343
BX114. Print newline on interruption stop. @98
SX115\>X34. Put space before \\{end_write_token}. @1371
BX116. Don't confuse \\{glue_order} with \\{stretch_order}. @838
TX117. Set $\\{max_dimen}\gets\hbox{\it'7777777777\/}$, not {\it'777777777}. @421
MX118. Make |\global\textfont| legal. @1211
BX119. Fetch |\the\textfont| with \\{equiv}, not \\{fam_font}. @415
BX120. Call $\\{new_ligature}(f,l,\ldots)$ not $(f,c,\ldots)$. @1035
RX121. Make \\{show_box} work on random garbage. @174,177
DX122. Count reference to \\{zero_glue} from \\{cond_math_glue}. @1171
* 23 Jul 1982
RX123. Allow $\\{avail}=\\{null}$ when undumping. @1312
BX124\>X110. Set $\\{width}(\\{glue_ptr}(p))$, not $\\{width}(p)$. @679
AX125. Put \\{begin_file_reading} inside the \\{start_input} loop. @537
BX126\>X116. Don't confuse \\{glue_stretch} with \\{stretch_order} [the previous
	fix went only half\-way]. @838
BX127. Negate $x$ when calculating badness of shrinkage. @667,678
LX128\>X121. Remove dangling {\bf else} that parses wrong. @174
IX129\>X28. Print newline before |{|, not after |}|, when tracing commands. @299
IX130. Remove colon from overfull box messages. @663,675
DX131\>X97. Compute \\{page_goal} properly when the first box arrives after
	inserts. @1001
BX132. Don't confuse \\{page_size} [now \\{page_goal}] with \\{best_size}. @1017
AX133. Put heldover insertions at front of contribution list. @1023
SX134\>X88. Output stats before closing |DVI| file, since the latter
	decreases \\{font_ptr}. @1333
TX135. Don't call a |\vbox| an |\hbox|. @674
TX136. Fix misplaced {\bf end} caused by editing error. @675
* 24 Jul 1982
DX137. Don't \\{eq_destroy} any paragraph shape when \\{par_shape} is null. @275
IX138. Omit blank before |\message| at the beginning of a line. @1280
AX139\>X104. Don't try to split an insertion when \\{best_node} isn't the
	split one. @1021
LX140. Correct another case of `{\bf if} $x\land y$' misunderstood by Pascal.
	@1021
IX141. Provide diagnostic info about insertions via |\showlists|. @986
IX142. Add `|inside a group|' to clarify a warning message. @1335
IX143. Report \\{prev_depth} on a separate line in |\showlists|. @219
SX144. Back up input to avoid unexpected clobberage of \\{cur_tok}. @1090
# Wow what a bug: \\{new_graf} calls \\{build_page}, which invokes the
	output routine, after which `\/{\bf goto} \\{reswitch}' is a {\sl disaster}.
DX145. Add insertion glue to \\{page_so_far} instead of subtracting it from
	the goal. @1009
IX146. Put extra blank line before overfull box warning. @660
CX147. Define break at kern consistently between horizontal and vertical lists. @973,1000
DX148. Renumber so that math nodes are nondiscardable. @147
TX149. Correct the \\{char_kern} macro: |#|, not $f$. @557
FX150. Decrease $l$ after reconstituting discretionary break. @916
EX151. Simplify the hyphen routine, knowing that $\\{link}(s)=\\{null}$. @918
FX152. Initialize $r\gets q$ in discretionary destruction routine. @883
* 25 Jul 1982
AX153. Don't add interline penalty after last line of paragraph. @890
IX154. Adjust spacing in diagnostic messages. @245
DX155. Avoid simultaneous use of \\{temp_head} by \\{prune_page_top} and the
	page builder. @1017
FX156. Clear the \\{post_break} field of simple discretionaries. @916
AX157. Split \\{offset} into independent variables \\{term_offset},
	\\{file_offset}. @54,57,58
# Am freezing current program as version $-0.25$; a week of TUG lectures
	begins tomorrow.
* 5 Aug 1982
IX158. The `|.err|' file should be `|.log|' instead. @534
GX159. Allow |\special| strings to contain more than 256 bytes. @585,1368
MX160\>X99. Undo ``correction'' to a non-bug. @1034
IX161. Suggest |\&| in help message for unexpected |&|. @1128
GX162. Make `|E|' a standard option for exiting. @84
GX163. Restore the use of dead cycles \`a la \TeX78. @1024,1054
# The previous six changes were suggested during discussions with \TeX82 class.
SX164. Fix global variable conflict between \\{open_log_file} and \\{new_font}. @1257
CX165. Allow optional `|=|' when assign to font parameter. @1253
FX166. Set \\{cur_val} after increasing the number of font parameters. @580
DX167. Set \\{hash_brace} when matching `|{|'. @476
IX168\>X88. Clarify meaning of statistics printed. @1334
GX169. Change |DVI| format to include design size. @602,1260
DX170. Introduce \\{def_ref} for \\{runaway} messages. @306
MX171. Restore \\{cur_cs} before calling \\{scan_toks}. @1226
AX172\>X157. Update \\{print_nl} to dual offset conventions. @62
AX173\>X163. Move endgame logic inside \\{main_control}, because the output
	routine becomes active. @1054
* 6 Aug 1982
CX174. Allow |INITEX| to load format files. @1337
EX175. Conserve input stack space by deleting finished token lists. @325
IX176\>X74. Print the opening `|**|' in the transcript file. @534
# Now ready to try breaking new ground in |TRIP|.
SX177. Preserve \\{align_state} from tokens deleted online. @88
DX178. Set $t$ in all branches of \\{scan_toks}. @473
SX179. Change `$\\{cur_cmd}\le\\{right_brace}$' to `$\\{cur_tok}\le
	\\{right_brace_limit}$'; otherwise |\relax| gets through. @477
CX180. Allow optional |=| when setting |\spacefactor|; disallow zero. @1243
BX181. Change \\{vpackage}(\\{head}) to \\{vpackage}(\\{link}(\\{head})). @796
# Shades of 1978!
LX182. Insert missing {\bf begin} \dots{ \bf end}. @798
* 7 Aug 1982
LX183. Keep \\{trie_max} declared in non-|INITEX| [later rescinded]. @950
DX184. Watch out for empty token list when copying. @466
DX185. Free unused reference count slot when defining |\everypar|. @1226
GX186\>X163. Introduce |\maxdeadcycles|. @1012
# I believe the \\{line_break} routine has passed its test perfectly.
SX187. Don't put discretionary after |-| inside a discretionary. @1039
CX188. Change `|\minus|' to `|\minusthe|' [this feature retracted later]. @413
BX189. Change \\{cur_p} to $r$ (three places). @875
AX190. Increase range of \\{hc} to \\{halfword}; otherwise end-of-word mark
	might match a vacant entry in the trie. @892
FX191. Initialize $b$ in \\{shift_case} routine. @1288
EX192. Don't back up if a space follows a decimal fraction. @452
BX193. Don't confuse \\{glue_base} with \\{dimen_base}. @1145
LX194. Guard against anomalous floating-point values in glue display. @186
* 8 Aug 1982
SX195. Avoid infinite loop when |\outer| leads to runaways. @339
# I worked on that problem about two hours before fixing it.
IX196. Move final \\{debug_help} to \\{succumb}, except in batch mode. @93
RX197. Insert kern after spanned box, to defeat access to floating point. @808
* 9 Aug 1982
CX198. Include |\leftskip| and |\rightskip| in displayed equations [rescinded
	later]. @1199
IX199. Trace line-break computations if $\\{tracing_stats}>2$. @846,856
DX200. Keep \\{prev_p} up to date when passing a string. @867
# Now stepping through math stuff; a lot is working.
DX201. Set $\\{link}(p)\gets z$ when making a fraction. @747
CX202. Don't reset space factor when beginning |\valign|. @775
IX203. Don't show glue setting if $\\{glue_sign}=\\{normal}$. @186
DX204. Clear \\{glue_stretch} and \\{glue_shrink} when creating an unset box. @801
BX205. Do \\{vpack} in hmode and vice versa when aligning. @804
AX206. Remove fallacious call to \\{confusion} after alignment in display. @1206
AX207. Don't test $\\{mode}=\\{vmode}$ in display, test $\\{nest_ptr}=1$. @1145
FX208. Show an \\{inner_noad} as well as the other types. @690,696
DX209. Renumber \\{mu_glue} and \\{cond_math_glue} so that the glue display logic
	works. @149
BX210. Don't confuse \\{cur_size} with \\{cur_style}. @703
FX211. Advance $p\gets q$ during second pass over mlist. @761
IX212. Add helpful hint about |\tracingonline=1|. @1293
TX213. Delete spurious statement left from sloppy editing. @710
DX214. Change the subtype when \\{mskip} becomes \\{hskip}. @732
FX215. Don't forget to use the remainder when computing math glue. @716
IX216\>X199. Improve paragraph diagnostics using \\{short_display}. @857
IX217\>X199. Introduce \\{artificial_badness} for better diagnostics. @854,856
* 11 Aug 1982
AX218. Introduce \\{char_box} subroutine so that \\{var_delimiter} adds italic
	correction. @709
SX219. Save font and char in local variables of \\{make_math_accent}, since
	it can be recursive. @738
FX220. Call \\{error} after decrying an invalid character. @346
* 12 Aug 1982
IX221\>X199. Install new format for showing break nodes. @846
# I have been testing \\{line_break} and I think it's working fine.
BX222. Change $q$ to $p$, in order to catch empty alignments. @812,1206
SX223. Disallow third part of discretionary in math mode. @1120
DX224. Don't change \\{tail} if discretionary third part is empty. @1120
IX225. Say |nonscript|, not |non_script|. @189
SX226. Inhibit math if |\scriptfont3| is improper. @1195
IX227\>X199. Introduce {\tt\@}|firstpass| and {\tt\@}|secondpass| comments. @863
TX228. Change $p$ to $r$ when you mean $r$. @1204
IX229\>X108. Say |page|, not |pages|, if there's only |1|. @642
IX230. Insert space before |[]| on truncated |\showlists|. @182
* 28 Aug 1982
# Back from vacation after having looked at hardcopy listing of |TRIP| test.
GX231. Allow |dm| as a unit [later |.5dm1| will be |.5\dimen1|]. @455
IX232\>X108. Singularize |prevgraf 1 lines|. @219
IX233. Omit trailing zero count registers when showing completed page numbers. @638
LX234. Avoid clobbering $a$ by introducing a new local variable $t$. @986
DX235\>X216. Fix diagnostic printing of discretionaries. @858
IX236. Don't show unset stretch/shrink that's zero. @185
CX237\>X198. Make |\halign| in displays consistent with other displays. (Namely,
	ignore |\leftskip| and |\rightskip| in nonaligned displays;
	respect the paragraph shape in aligned displays.) @800,1199
IX238. Parenthesize `|If you're confused ...|'. @403
IX239. Say `|\fraction|', not `|\xabovex|'. @697
FX240. Remember to {\bf return} when you should. @1153
PX241. Use absolute value to make sure {\bf div} is unambiguous. @737
BX242\>X218. Don't confuse depth with height. @709
BX243. Use $\\{delta}-\\{height}$, not $\\{height}-\\{delta}$. @736
BX244. Increase \\{shift_down} to increase the clearance. @745
IX245. Don't back up after improper use of |\the|. @428
IX246. Don't give |0pt| as the default result when looking for \\{tok_val}. @428
FX247. Initialize \\{second_indent} in the easy case. @848
FX248. Package the equation number. @1204
QX249. Don't resort to $v\gets\\{max_dimen}$ when glue doesn't stretch or
	shrink. @1148
IX250. Insert newline before showing current |\botmark|.
FX251. Call \\{error} after giving error message. @784
AX252. Change implementation of |\number|; it should \\{scan_int}, not
	something internal. @471
PX253. Introduce symbolic constants like \\{format_area_length}. @524
PX254. Change \\{quit} to \\{jump_out}, since some compilers treat \\{quit}
	as a reserved word. @81
LX255. Add more parentheses to get proper parsing. @1260
IX256. Say |please| in order to be friendly (or at least polite). @360
BX257. Don't confuse \\{cur_vcmd} with \\{cur_chr}. @508
IX258. Use |&| instead of |!| to specify a preloaded format. @1337
TX259\>X177. Correct |s3| to |s4|. @88
GX260. Introduce new primitive |\mathchardef|, to save space and time. @1224
CX261. Use the |[]| convention for noads as well as nodes. @692
TX262. Correct spelling in call to \\{primitive}: |\xatopx| should be |\xoverx|
	[later renamed, thank goodness]. @1178
* 30 Aug 1982
RX263. Don't fetch \\{link}(\\{null}) in malformed list. @175
SX264. Initialize \\{align_state} at a better time so that \\{align_peek}
	doesn't see |&| or |\span|. @785,791
SX265. Outlaw preamble interfering with $\\{align_state}=0$. @789
CX266. Add level of grouping to alignment to tabskip locality. @774
FX267. Check \\{align_state} when scanning $\langle u_j\rangle$. @783
AX268. Move `\\{unsave}; \\{new_save_level}' from \\{main_control} into
	\\{fin_col}. @791,1131
SX269\>X180. Remember \\{cur_chr} when you're looking for optional `|=|'. @1243
TX270. Change $q$ to $r$ [in code now obsolete]. @804
IX271. Disable interrupts during \\{back_error} so that help messages aren't
	clobbered. @327
SX272. Introduce \\{slow_print} for printing control sequences. @60
IX273. Initialize \\{del_code}(|"."|$)\gets0$ for error recovery. @240
SX274. Call \\{end_file_reading} before calling \\{check_outer_validity}. @362
IX275. Don't delete an extra `|}|' when |\par| will help find a runaway. @395
* 31 Aug 1982
BX276. Don't confuse \\{thin_muskip} with \\{thin_muskip_code}. @413
FX277\>X266. Recover from error if new \\{align_group} ends abnormally. @1132
IX278. Recover from error if |\par| occurs when $\\{align_state}<0$. @1094
CX279. Make |\hskip\the\thinmuskip| and |\mskip\the\baselineskip| erroneous. @413
GX280. Add |\muskip| and |\setmuskip| analogs to |skip| and |\setskip|. @413,1228
EX281. Don't output |pop| right after |push|. @601
# The |TRIP| test looks right; now to test for wasted memory.
# When memory should be empty I find $\\{dyn_used}=18$, $\\{var_used}=267$.
* 1 Sep 1982
# Made special |MEMTEX| program, designed to track all memory allocation.
DX282. Delete reference to \\{last_glue} when a page is packaged. @1017
IX283. Include \\{save_stack} in the \\{search_mem} debugging routine. @285
CX284. Disallow |\vfill| in restricted horizontal mode. @1095
# Most of the memory locations I thought were wasted were actually in good use.
# Total 192 hours (approx) debugging time so far since July 15.
* 2 Sep 1982
# Now looking at all zero counts in profile and extending |TRIP|.
EX285. Simplify the creation of |vtop| boxes. @1087
CX286. Set $\\{space_factor}\gets1000$ after |\hbox|. @1076
PX287. Introduce preamble into |DVI| format. @617
SX288. Give special \\{chr_code} to |\relax|. @265
IX289. Don't show `|(null)|' when token list is null, just show nothing. @295
EX290. Delete the procedure \\{write_name_string}, which is never used.
CX291. Rename |\xabovex| to |\abovewithdelims|; do the same for
	|\xatopx| and |\xoverx|. @1178
QX292. Improve \\{clean_box} so that it recognizes cleanliness better. @720
IX293. Report a |Missing delimiter| more meaningfully. @1161
RX294. Give \\{endv_token} a \\{chr} code of 128 so that it will end a file name. @289
RX295. Test present of math fonts {\sl after\/} parsing an mlist, not
	before. @1138,1195
IX296. Omit `|recent contributions|' and/or `|current page|' when they are
	empty. @218,986
IX297. Display what \TeX\ has deleted after improper discretionary list
	has arisen. @1121
IX298. Show what math character was undefined. @723
IX299. Improve the |Incompatible magnification| error; break it into two lines. @288
DX300. Put new cases into \\{flush_node_list}, to recycle mlist noads. @698
* 6 Sep 1982
FX301\>X300. Insert a necessary `{\bf goto} \\{done}' in that new material. @698
# It took two hours to diagnose that {\bf goto} problem.
TX302\>X295. Change `|2|' to `|3|' in help message for extension fonts. @1195
IX303. Add a special note if material is being held over for the next output. @986
RX304. Divide before multiplying in \\{make_left_right}, to avoid overflow. @762
IX305. Introduce the \\{box_error} routine. @992
FX306. Clear \\{arith_error} after overflow has been reported. @460
BX307\>X249. Don't confuse \\{stretch} with \\{glue_stretch}. @1148
DX308. Set $\\{glue_sign}\gets\\{normal}$ when packaging with glue ratio
	zero. @558,664
AX309. Test for overflow before attaching the sign. @448
# That all worked! Now trying |min_quarterword| negative.
LX310. Take absolute value before applying {\bf mod} in \\{new_trie_op}. @944
LX311. Say $\\{qi}(c)$, not $c$, when testing |TFM| flags [now obsolete]. @573
LX312. Initialize \\{token_ref_count}(\\{def_ref}) to \\{null}, not zero. @473
LX313. Change the type of \\{vsplit} parameter $n$ from \\{quarterword} to
	\\{eight_bits}. @977
LX314. Initialize \\{null-delimiter} different form \\{null_character}. @685
LX315. Insert \\{qi} twice in \\{scan_delimiter}. @1160
FX316. Insert \\{qi} in \\{scan_math}. @1151
FX317. Insert \\{qo} in \\{fetch}. @722,723
FX318. Insert \\{qi} in \\{set_math_char}. @1155
FX319. Insert \\{qi} in \\{math_ac}. @1165
FX320. Insert \\{qo} in \\{mlist_to_hlist}. @755
IX321. Use brackets around 8-bit characters in \\{print_ASCII}. @68
IX322. Include \\{hyph_list} in the \\{search_mem} debugging routine. @933
# Now compiling non-|INITEX| to try an industrial-strength version.
LX323. Add {\bf return} to \\{final_cleanup}, because some Pascal compilers
	insist that each label be used. @1335
DX324. Compute \\{par_token} when undumping. @1314
* 11 Sep 1982
IX325. Emit newline before file name, if near end of line. @537
CX326. Define |\ifx| for arbitrary tokens. @507
* 12 Sep 1982
IX327. Don't ask users to type |x| twice before exiting. @84
GX328. Install new features |\openin|, |\read|, |\ifeof|, |\closein|; rename
	existing |\open|, |\send|, |\close| to be |\openout|, |\write|,
	|\closeout|. @209,313,1275
GX329. Install new feature |\expandafter|. @368
PX330. Change the default file area from `|<TeX>|' to `|TeXinputs:|'. @574
* 13 Sep 1982
GX331. Install new feature |\string|. @472
AX332. Remove spurious space printed by \\{sprint_cs}. @263
# All tests passed now! But when I played with the system I found another bug
	(undetected by |TRIP|):
FX333. Set $r\gets s$ after matching macro parameter tokens. @397
* 16 Sep 1982
IX334\>X199. Introduce serial numbers in line-break records, improving
	readability and independence. @846
IX335. Don't abort when \\{file_name_size} is exceeded. @519
* 17 Sep 1982
IX336. Remove unwanted period from font capacity message. @567
* 18 Sep 1982
GX337\>X329. Make |\expandafter| more powerful by moving it from semantics
	to syntax [i.e., from stomach to mouth]. @368
* 19 Sep 1982
IX338. Improve error recovery for `|Missing number|'. @415
* 22 Sep 1982
QX339. Suppress italic correction between letters in math mode except in math
	fonts. @752
* 24 Sep 1982
PX340. Define $\\{null}=\\{mem_bot}$, not \\{min_halfword}, because there's
	a reference to \\{link}(\\{null}) in \\{try_break}. @115
DX341. Initialize $\\{str_start}[0]\gets0$. @47
IX342. Avoid blank space at beginning of line. @638
DX343. Set type of new box in math mode to \\{ord_noad}, not \\{inner_noad}. @1076
* 28 Sep 1982
# Here are the first changes made to the preliminary listing of \TeX82 that was
	published by the \TeX\ project earlier this month.
F520. Insert the missing cases \\{letter} and \\{other_char} after
	\\{x_token} looks ahead. @1038
C521. Change `|\pause|'  to `|\pausing|'. @236
D522. Reset \\{overfull_rule} when determining tabskip glue. @804
A523. Fix the logic for scanning |\ifcase| [in obsolete syntax---everything
	is still done with braces since `|\fi|' doesn't exist yet]. @509
* 30 Sep 1982
I524. Change |"0.0"| to |"?.?"| (suggested by DRF). @186
* 2 Oct 1982
Q525. Use conditional thin spacing next to `Inner' noads. @764
Q526. Make thick spaces conditional. @766
* 4 Oct 1982
P527. Increase \\{trie_size} from 7000 to 8000, because of Frank Liang's improved
	(but longer) hyphenation patterns. @11
* 6 Oct 1982
F528\>X330. Change the string lengths to match the new \\{\TeX_format_default}. @520
# Version 0 of \TeX\ is being released today!
* 8 Oct 1982
B529. Fix a blunder: I decreased $h$ mod a quarterword when it should have
	been decreased mod \\{trie_op_hash_size} (HWT). @944
* 9 Oct 1982
P530\>X258. Fix a typo (`|!|' not `|&|') in the |WEB| documentation. @524
F531. Remember to call \\{initialize} if a different format was preloaded
	(Max D{\'\i}az). @1337
# Version 0.1 incorporates the above changes.
* 12 Oct 1982
G532. Add the `|\immediate|' feature, by popular request. @1375
# Version 0.2 incorporates this (somewhat extensive) change.
* 13 Oct 1982
P533. Introduce new |WEB| macros so that \\{glue_ratio} is more easily changed. @109
# I began writing {\sl The \TeX book\/} today: edited the old preface and
	searched in the library for quotations.
* 14 Oct 1982
B534. Change the type of \\{hd} to \\{eight_bits}; it's
	not a \\{quarterword} (HWT). @649
S535\>X281. Revise the optimization of\/ |DVI| commands: It's not always safe to eliminate
	\\{pop} when the preceding byte is \\{push}, since |DVI| commands
	have variable length! (Embarrassing oversight caught by DRF.) @601
* 15 Oct 1982
C536. Test `$\\{prev_depth}>\\{ignore_depth}$', not `$\ne$'. @679
# Version 0.3 incorporates the above changes.
* 16 Oct 1982
P537. Omit definition of \\{align_size}; it's never used (Bill Scherlis). @11
I538. Inhibit error messages when packaging box 255. @1017
* 21 Oct 1982
A539\>X145. Subtract $\\{width}(q)$ from \\{page_goal}, don't add it to
	$\\{page_so_far}[1]$. @1009
# Version 0.4 incorporates the above changes.
* 22 Oct 1982
P540. Increase the amount of lower (variable-size) memory from 12000 to 13000,
	since the \TeX\ program listing now needs about 11500. [At this time
	there still is a fixed boundary between upper and lower memory.] @12
G541. Add a new parameter |\boxmaxdepth|. @1086
# Version 0.5 incorporates the above changes.
* 26 Oct 1982
B542. Fix an off-by-one error caught by Gabi Kuper and HWT.
	(I forgot `${}+1$'). @1317
B543. Fix the spacing of displayed control sequences: \\{print_cs} should base its
	decision on $\\{cat_code}(p-\\{single_base})$, not $\\{cat_code}(p)$. @262
# The |TRIP| test detected this bug, but I didn't notice.
* 27 Oct 1982
S544. Set \\{math_type} before saying $\\{fetch}(\\{nucleus}(q))$, since
	fetching can have a side effect. @752
* 28 Oct 1982
G545. Install a major change: Fonts now have identifiers instead of code letters.
	Eliminate the `|\:|' primitive, and give corresponding new
	features to `|\the|'. @209
# Actually I began making these changes on October 26, but I needed two days
	to debug them and to put Humpty Dumpty together again.
# At this time I'm also drafting macros for typesetting {\sl The \TeX book}.
# The above changes have been incorporated into Version 0.6.
* 30 Oct 1982
# After years of searching, I've finally found a definitive definition of
	the printer's point; and (unfortunately) my previous conjecture was
	wrong. The truth is that $\rm83\,pc=35\,cm$, exactly;
	so I am changing \TeX\ to conform.
C546. Revise unit definitions for the `real' printer's point. @458,617
# Version 0.7 incorporates the above.
* 1 Nov 1982
# Oops! Retract error \#546, and retract \TeX\ Version 0.7;
	the source of my information about points was flaky after all.
	My original suppositions were correct,
	as confirmed by NBS Circular 570.
* 4 Nov 1982
C547. Revise the definition of |dd|, conforming to the definitive value
	shown me by Chuck Bigelow. @458
R548\>545. Introduce ``frozen'' copies of
	font identifiers, to be returned by |\the\font|, so that font
	manipulation is more robust. @1257
* 5 Nov 1982
D549. Reset \\{looseness} and paragraph shape when beginning a |\vbox|. @1083
* 6 Nov 1982
D550. De-update \\{align_state} when braces are in constants. @442
I551\>X294. Improve error recovery for bad alignments. @1127
# Today I wrapped up Chapters 4 and 5.
* 8 Nov 1982
G552. Give more power to |\let|: the right-hand side needn't be a control
	sequence. @1221
I553. Amend \\{show_context} to say
	`$(\\{base_ptr}=\\{input_ptr})\lor{}$'; otherwise undefined control
	sequences can be invisible in unusual cases (John Hobby). @312
A554. Compute demerits more suitably by adding a penalty squared, instead of
	adding penalties before squaring. @859
# Previously a slightly loose hyphenated line followed by a decent line
	was considered worse than a decent hyphenated line followed by
	a quite loose line.
* 10 Nov 1982
E555. Save a bit of buffer space by declaring \\{pool_file} only in
	|INITEX|. @50
* 11 Nov 1982
I556. Introduce a new context indicator to clarify \TeX's scanning state:
	A special type
	called \\{backed_up} is distinguished from other kinds of \\{inserted}
	lists; it is called `recently read' or `to be read again', while
	others are called `inserted'. @314
I557. Append a comment, `|treated as zero|', to the missing-number message. @446
I558. Ignore the settings of\/ |\hfuzz| or |\vfuzz| if\/ |\hbadness| or |\vbadness|
	is less than 100. @666,677
* 13 Nov 1982
# Major surgery on the program is planned for today, because of new ideas
	suggested by correspondence with MDS and other macro writers.
G559. Introduce a new |\tokens| register; this will be useful and easy to add,
	since \TeX\ already can handle |\everypar| and |\output|. @1227
C560\>X34. Change \\{get_x_token} to \\{get_token} when scanning an optional
	space; then a construction like
	|\def\foo{...}\foo| won't complain that |\foo| is undefined. @443
# This change was retracted when it was being debugged, because it could
	cause \\{endv} to abort the job. Then it was re-established again
	when I found that \\{endv} needed to be more robust anyway.
	[But it was eventually rescinded again.]
G561. Make |\span| mean `expand' in a preamble. @782
E562. Use three separate {\bf if\/} tests instead of
	`$\land$' in the inner loop of \\{get_next}, to gain efficiency. @342
R563. Introduce \\{get_r_token} so that assignments have uniform error
	messages and so that frozen equivalents cannot be changed. @1215
# I gave a few variables more mnemonic names as I made these changes.
C564. Move conditional statements from the semantics (`stomach') part of
	\TeX\ to the syntax (`mouth') part, by introducing `|\fi|'.
	Also introduce |\csname| and |\endcsname|. @372,489\hbox{--}500
# This makes macros much more predictable and logical, but it is by far
	the most drastic change ever made to \TeX. The program began to come
	back to life only after three days of solid hacking.
# Several other things were cleaned up as part of this change
	because it is now more natural to handle them differently.
	For example, a null control sequence has now become more logical.
# The result of all this is called Version 0.8.
* 18 Nov 1982
# Today I resumed writing Chapter 8. Tomorrow I'm $\,2^{14}$ days old!
* 21 Nov 1982
F565. Declare $c$ as a local variable for hyphenation (DRF). @912
E566. Omit the ``first pass'' and try hyphenations immediately,
	if\/ |\pretolerance| is negative (suggested by DRF). @863
R567. Don't ship out incredibly huge pages; they might foul up
	|DVI| files. @641
* 2 Dec 1982
G568. Add new features |\everymath| and |\everydisplay|. @1139,1145
G569. Add a new feature |\futurelet|. @1221
# The changes above have been incorporated into Version 0.9 of TeX.
* 7 Dec 1982
G570. Add a new |\endinput| primitive (suggested by FY). @362,378
* 8 Dec 1982
I571. Try \\{off_save}, if\/ |\par| occurs in restricted horizontal mode.
	(This avoids embarrassment if \TeX\ says `type a command or
	say |\end|', then when you type |\end| it says you can't!)
	[However, I soon retracted this change.] @1094
* 21 Dec 1982
A572. Redefine |\relax| so that its \\{chr} field exceeds 127. (This facilitates
	the test for end in \\{scan_file_name}.) @265
F573\>566. Call \\{begin_diagnostic} when omitting
	the first pass of line breaking. @863
A574. Fix the logic of glue scanning: In |\hskip-1pt plus2pt| the minus should
	apply only to the |1pt|. @461
* 23 Dec 1982
I575. Renumber the decimal codes in paragraph statistics for loose and tight
	lines; they were ordered backwards. @817
C576. Treat a paragraph that ends with leaders like a paragraph that
	ends with glue. @816
C577. Allow commas as alternates to radix points, for Europeans. @438
C578. Change |\hangindent| to a normal dimension parameter. [It had been
	a combination of\/ |\hangindent| and |\hangafter|, with special
	syntax.] @247
G579. Make |\prevgraf| accessible to users. @422,1244
G580. Split |\clubpenalty| off from |\widowpenalty|. @890
# I'm typing Chapter 14 while making these changes.
* 24 Dec 1982
S581. Use \\{back_input} instead of {\bf goto} \\{reswitch} when
	inserting |\par|, because |\par| may have changed. @1095
* 25 Dec 1982
# It's 10pm after a very Merry Christmas!
I582\>X328. Don't prompt for a new file name if\/ |\openin| doesn't find a file. @1275
G583. Add a new |\jobname| primitive. @472
I584. Give the user a way to delete the dollar sign, when \TeX\ decides
	to insert one. @1047
C585. Allow optional equals after |\parshape|, and implement |\the\parshape|.
	@423,1248
* 26 Dec 1982
I586. Add an \\{if_line_field} to the condition stack entries,
	so that more informative error messages can be given. @489
D587\>549. Introduce a \\{normal_paragraph} procedure, since initialization is needed
	also within |\insert|, |\vadjust|, |\valign|, |\output|. @1070
* 27 Dec 1982
G588. Give users access to |\pagetotal| and |\pagegoal|. (Analogous to
	\#679 and \#585, but simpler.) @1245
I589\>X199. Introduce |\tracingpages|, allowing users to see
	page-optimization calculations. Also split |\tracingparagraphs| off from
	|\tracingstats|. @987,1005,1011
# The changes above have been incorporated into Version 0.91 of \TeX.
* 31 Dec 1982
P590. Break the \\{build_page} procedure into two parts, by extracting
	the section now called \\{fire_up}. [This is necessary because
	some Pascal compilers, notably for IBM mainframes, cannot
	deal with large procedures.] @1012
S591\>564. Make |\ifodd1\else| legal by introducing \\{if_code}. @489
Q592. Improve alignments when columns don't occur: Don't append null boxes
	for columns missing before |\cr|, and zero out the tabskip
	glue after nonpresent columns. @802
I593. Make the error message about overfull alignment more intelligible.
	@801,804
# The changes above have been incorporated into Version 0.92 of \TeX82,
	which was the last version of 1982,
	completed at 11:59pm on December 31.
* 3 Jan 1983
# Today I'm beginning to write Chapter 15, and
	planning the |\output| routine of |plain.tex|.
C594\>X186. Change the logic of \\{its_all_over}; use \\{max_dead_cycles}
	here too, instead of the fixed constant~100. @1054
F595\>X34. Don't forget to \\{pop_nest} when an insert is empty. Also disallow
	optional space after |\insert|$\,n\,$|{...}|. @1100
* 4 Jan 1983
C596\>541. Use the |\boxmaxdepth| that's declared inside a |\vbox| when packaging it.
	@1086
C597. Rename |\groupbegin| and |\groupend| as |\begingroup| and
	|\endgroup|. @265
G598\>594. Make |\deadcycles| accessible to users. @1246
Q599. Base the split insertions on natural height plus depth, not
	on \\{delta}. @1010
# The changes above have been incorporated into Version 0.93.
* 6 Jan 1983
D600. Add \\{push_math} to handle a case where I forgot
	to clear \\{incompleat_noad}. (This long-standing bug was
	unearthed today by Phyllis Winkler.) @1136
G601\>588. Add |\pageshrink|, etc., too. @1245
G602. Introduce new parameters |\floatingpenalty|, |\insertpenalties|. Also
	adopt a new internal representation of insertion nodes,
	so that |\floatingpenalty|, |\splittopskip| and |\splitmaxdepth|
	can be stored with each insertion. @140,1008
* 7 Jan 1983
Q603. Improve the rules for entering \\{new_line}, in particular
	when the end-of-line character is active. @343
* 9 Jan 1983
Q604. Distinguish between implicit and explicit kerns. @155,896
C605. Change the name |\ignorespace| to |\ignorespaces|. @265
C606\>560. Don't omit a blank space after |\def|, |\message|, |\mark|, etc.;
	the previous hodge-podge of rules is impossible to learn. @473
# The above changes appear in Version 0.94.
* 12 Jan 1983
# Beginning to write the chapters on math today.
G607. Add a new feature: active characters in math mode. @1151
* 15 Jan 1983
A608. Fix a surprise bug: `|$1-$|' treated the |-| as binary. @729
D609. Initialize \\{space_factor} inside discretionaries. @1117
* 16 Jan 1983
F610. Fix an incredibly embarrassing bug: I forgot to update \\{spotless} in the
	\\{error} routine!
# While fixing this, I decided to change
	\\{spotless} to a more general \\{history} variable, as suggested
	by IBMers who want a return code. @76,82,1335
I611. Replace two calls of \\{confusion} by attempts at error recovery, in places
	where `|This can't happen|' could actually happen. @1027,1372
* 18 Jan 1983
R612. Introduce the \\{normalize_selector} routine
	to protect against startup anomalies
	when the transcript file isn't open. Also make \\{open_log_file}
	terminate in some cases. @92,535
R613\>591. Insert |\relax|, not a blank space, to cure infinite
	loop like |\ifeof\fi| (LL). @510
G614. Change the old |\limitswitch| to |\limits|, |\nolimits|, and
	|\displaylimits|. Incidentally, this fixes a bug in the former
	positioning of integral signs. @682,749
C615. Give a |\char| in math mode its inherited |\mathcode|. @1151
Q616\>525. Make underline, overline, radical, vcenter, accent noads and |{...}|
	all revert to type Ord instead of type Inner. Introduce a new primitive
	|\mathinner|. (This fixes the spacing, which
	got worse in some ways after change \#525.) @761
# I'm working on Appendix G today.
* 19 Jan 1983
G617. Introduce a |\mathchoice| primitive. @1174
C618. Move |\input| from the stomach to the mouth. @378
C619\>X260. Introduce |\chardef|, analogous to |\mathchardef|. @1038,1224
G620. Change |\unbox| to |\unhbox| and |\unvbox|; also add |\unhcopy|. @1110
C621. Consider |\spacefactor|, |\pagetotal|, etc., as part of
	\\{prefixed_command}, even though they are always global. @1211
* 20 Jan 1983
C622. Switch modes when |\hrule| occurs in horizontal mode or |\vrule|
	in vertical. @1090,1094
G623. Add a new |\globaldefs| feature. @1211
* 21 Jan 1983
E624. Optimize the code, in places where it's important (based on
	frequency counts of \TeX\ usage
	accumulated during the past week): Introduce \\{fast_get_avail}
	and \\{fast_store_new_token}; reduce procedure-call overhead
	in \\{begin_token_list}, \\{end_token_list}, \\{back_input},
	\\{flush_node_list}; change some tests from `{\bf if} $a\land b$' to
	`{\bf if}~$a$ {\bf then if}~$b$'. @122,371
* 22 Jan 1983
E625. Save space in math lists: Don't insert penalties within restricted
	horizontal mode; simplify trivial boxes. @721,1196
S626. Fix a surprising oversight in the \\{rebox} routine:
	Ensure that $b$ isn't a vbox. @715
C627\>545. Make |\nullfont| a primitive, so that \\{cur_font} always
	has a value. (This is a dramatic improvement over \TeX78, where a
	missing font was a fatal error called `|Whoa|'!) @552
* 24 Jan 1983
I628\>586. List all incomplete |\if|'s when the job ends. @1335
* 29 Jan 1983
C629\>552. Change initialization of \\{align_state} so that |\halign\bgroup|
	works. @777
* 30 Jan 1983
D630\>625. Be sure to test `\\{is_char_node}($q$)' when checking for a trivial
	box. @721
# By extraordinary coincidence, this bug was caught when somebody
	used font number~11 ($=\\{kern_node}$) in the second character
	of a list of length~2!
I631\>X168. Improve format for stats at end of run, as suggested by DRF. @1334
# The changes above have been incorporated into Version 0.95.
C632. Don't ignore the space after a control symbol (except `|\ |'). @354
P633. Remove all trailing spaces at the right of input lines,
	so that there's perfect compatibility with IBM systems that
	extend short lines with spaces. @31
* 3 Feb 1983
I634. Assume that a \\{math_accent} was intended, after giving an error
	message in the case $\\{mmode}+\\{accent}$. @1165
G635. Add new primitives |\iftrue| and |\iffalse|. @488
* 6 Feb 1983
A636\>X304. Improve the accuracy of fixed-point arithmetic when
	calculating sizes for |\left| and |\right|. (I had started by
	dividing \\{delimiter_factor}, not \\{delta1}, by 500.) @762
* 12 Feb 1983
C637. Change the name |\delimiterlimit| to |\delimitershortfall|. @248
C638. Make |\abovewithdelims..| equivalent to |\above|; change the
	order of operands so that delimiters precede the dimension. @1182
C639\>607. Remove the kludgy math codes introduced earlier;
	make |\fam| a normal integer parameter and allow |\mathcode|
	to equal $2^{15}$. @1233
R640. Don't let |\spacefactor| become more than $2^{15}$. @1233,1243
# I finished drafting Chapter 17 today.
* 14 Feb 1983
I641\>639. Replace octal output (\\{print_octal}) by hexadecimal (\\{print_hex})
	so that math codes are clearer. @67
F642\>619. Don't forget \\{char_given} in the \\{math_accent} routine. @1124
* 17 Feb 1983
C643\>622. Switch modes when |\halign| occurs in horizontal mode, or |\valign|
	in vertical mode. @1090,1094
* 18 Feb 1983
I644. Add a new feature |\tracingrestores|. This requires a new procedure called
	\\{show_eqtb}, whose code can be
	interspersed with the \\{eqtb} definitions. @252
* 25 Feb 1983
I645\>622. Suggest using |\leaders| when the user tries a horizontal rule
	in restricted horizontal mode. @1095
* 27 Feb 1983
I646. Specify the range of source lines, when giving warning messages
	for underfull or overfull boxes in alignments. @662,675
# Why did it take me all day to type the middle part of Chapter 18?
* 4 Mar 1983
G647. Introduce a new feature |\xcr| (suggested by LL). [Changed later to
	`|\crcr|'.] @785
I648\>631. Subtract out \TeX's own string requirements from the stats. @1334
* 6 Mar 1983
G649. Add new features |\everyhbox| and |\everyvbox|. @1083,1167
* 9 Mar 1983
R650\>X295. Avoid accessing \\{math_quad} when the symbol fonts aren't known
	to be present. @1199
P651\>533. Introduce \\{float} and \\{unfloat} macros to aid portability (HWT). @109
C652. Introduce new names |\abovedisplayskip| and |\belowdisplayskip| for
	the old |\dispskip|; also |\abovedisplayshortskip| and
	|\belowdisplayshortskip| for the old |\dispaskip| and |\dispbskip|. @226
* 10 Mar 1983
C653. Unbundle |\romannumeral| from |\number| (suggested by FY). @468
* 12 Mar 1983
C654. Ignore leading spaces in \\{scan_keyword}. @407
* 14 Mar 1983
E655\>631. Use \\{write} and \\{write_ln} directly when printing stats. @1334
* 16 Mar 1983
Q656\>602. Refine the page-break cost function (introducing `\\{deplorable}',
	which is not quite `\\{awful_bad}'), after suggestion by LL. @974,1005
# The changes above have been incorporated into Version 0.96.
* 18 Mar 1983
G657. Add a new feature |\everyjob| suggested by FY. @1030
* 19 Mar 1983
I658. Don't treat left braces specially when showing macros. @294
C659. Ignore blanks that would otherwise become undelimited arguments. @393
* 21 Mar 1983
F660\>X280. Make |\lastskip| handle \\{mu_glue} as well as ordinary glue. @424
C661\>561. Expand only one level in a preamble |\span|. @782
* 22 Mar 1983
C662. Let a single |#| suffice in |\tokens|, |\message|, etc. (The previous rule,
	in which |##| was always required as in macros, was a loser especially
	in |\write| where you had to say |####|!) @477
C663\>X328. Require the keyword `|to|' in |\read|. (This will avoid the common error
	of an incomplete constant when no space appears
	before the |\cs|.) Also allow terminal
	I/O as a default when a stream number is out of range. @482,1225,1370
* 26 Mar 1983
C664. Replace |\ifeven|\<countnumber> by |\ifodd|\<number>, for better
	consistency of language. @504
S665\>564. Introduce the \\{change_if_limit}, to overcome a big surprise
	bug relating to |\if\if aabc\fi|. @497
# Such examples show that \\{cur_if} might not be current,
	in my original implementation.
* 28 Mar 1983
G666\>X326. Tolerate non-characters as arguments to |\if| and |\ifcat|. @506
C667. Change `|absent|' to `|void|', a better word. @487
C668. Clear the \\{shift_amount} in |\lastbox|, since I don't
	want to figure out what it means in all cases. @1081
* 29 Mar 1983
I669. Wake up the terminal before giving an error message. (This
	means a special \\{print_err} procedure is introduced.)
	(Suggested by DRF.) @34,73
* 1 Apr 1983
# Today I finished Chapter 21 (boxes) and began to draft Chapter 22 (alignments).
G670. Allow periodic preambles in alignments. @793
C671. Make |\leaders| line up according to the smallest
	enclosing box. @627,636
Q672. Allow hyphenation after whatsits (e.g., after items for an index). @896
* 2 Apr 1983
Q673. Call \\{build_page} when |\par| occurs in vertical mode. @1094
C674. Clear \\{aux} in \\{init_row}, for tidyness. @786
* 4 Apr 1983
C675. Let digits switch families in math mode. @232
* 7 Apr 1983
Q676\>602. Refine the test for not splitting an insertion. @1008
* 8 Apr 1983
C677\>647. Rename |\xcr| as |\crcr|, at LL's request. @780
* 9 Apr 1983
# Took a day off and had a chance to help print a sample page on
	a 150-year-old letterpress in Murphys, California.
* 11 Apr 1983
I678. Recover more sensibly after a runaway preamble. @339
* 12 Apr 1983
C679\>X328. Make |\read| span several input lines, if necessary to get
	balanced braces. @482
* 14 Apr 1983
S680. Fix a subtle bug found by JS: \S882 can make $q$ a \\{char_node},
	so we need to test `{\bf if} $\lnot\\{is_char_node}(q)$'.
	[Actually I discovered much later that the real bug was
	to omit `{\bf else}' at this point.] @881
* 15 Apr 1983
C681. Make |\uppercase| and |\lowercase| apply to all characters, regardless
	of category. @1289
# 7:30am. After working all night, I completed a draft of the manual thru
	Chapter 22, for distribution to volunteer readers.
# 5pm. The changes above have been incorporated into Version 0.97.
* 17 Apr 1983
R682. Change `\\{small_number}' to `$0\,.\,.\,65$' in the
	hyphenation routine (DRF). @901
I683. Flush patterns in the input when the user tries |\patterns|
	outside of\/ |INITEX| (suggested by DRF). @1252
# Tomorrow I fly to England, where I'll lecture and write a paper about
	`Literate Programming' [{\sl Comp.~J. \bf27} (1984), 97--111].
* 14 May 1983
I684\>663. Improve the behavior of\/ |\read| from terminal
	(suggested by Todd Allen at Yale).
	[I'd forgotten to implement the extended stream numbers in \#663.
	Also, the prompt is now omitted if $n<0$.] @484
* 18 May 1983
I685. Restrict |\write| $n$ to the transcript file only, if $n<0$. @1350
C686\>X188. Unify the syntax for registers and internal quantities. (Remove
	primitives called `|\insthe|' and `|\minusthe|'; rename
	\\{scan_the} to \\{scan_something_internal}, and change its
	interface accordingly; clean up command codes generally.) @209,413
G687. Introduce new parameters |\hoffset|, |\voffset|. @617
* 24 May 1983
G688. Introduce a new parameter |\everycr| (suggested by MDS). @774,799
# Many macro writers and preliminary-manual readers have been requesting
	new features; I'll try to keep the language as concise and consistent
	as possible.
* 25 May 1983
G689. Introduce |\countdef|, |\dimendef|, etc.\ (suggested by DRF long ago,
	easy now in view of \#686). @1224
G690. Introduce |\advance|, |\multiply|, |\divide| (suggested by FY). @1240
G691. Introduce |\hyphenchar|; this requires a new command
	\\{assign_font_int}, plus minor changes to about 15 modules. @915
G692. Introduce |\skewchar| (easy because of \#691). @741
G693. Introduce |\noexpand|. (I had difficulty thinking of how to
	implement this one!) @358,369
G694. Introduce |\meaning|. @296
G695\>X231. Remove `|dm|' and `|vu|'; allow the more general `|.5\hsize|'. @455
C696. Change `|\texinfo| $f$ $n$' to `|\fontdimen| $n$ $f$'. @578
* 27 May 1983
G697. Add a new feature |\afterassignment| (suggested by ARK). @1269
C698\>619. Adjust the timing so that commands like `|\chardef\xx=5\xx|'
	behave sensibly. @1224
* 28 May 1983
C699. Ignore `|\relax|' as if it were a space, in math mode and in a few other
	places where |\relax| would otherwise be erroneous. @404
Q700. Improve |\mathaccent| spacing with respect to subscripts
	and superscripts (suggested by HWT). @742
* 30 May 1983
C701\>598. Terminate a job only when $\\{dead_cycles}=0$. @1054
# The changes above constitute Version 0.98.
* 3 Jun 1983
# I finished the draft of Chapter 23 (output routines) today.
G702. Allow |\mark| and |\insert| and |\vadjust| in restricted
	horizontal mode, and also in math mode. (This is a comparatively
	big change, triggered by the fact that |\mark| in a display
	presently causes \TeX\ to crash with `|This can't happen|'!)
	The global variable \\{adjust_tail} is introduced. @796,888,1085
* 6 Jun 1983
G703\>695. Replace (and generalize) the previous uses of\/ |ht|, |wd|, and |dp|
	in dimensions by introducing the new control sequences
	|\ht|, |\wd|, and |\dp|. @1247
I704. Display sub-parts of noads with the symbols |^| and |_| instead of
	|(| and~|[|. @696
C705\>694. Allow |A..F| in hex constants to be \\{other_char} as well as
	\\{letter}. @445
* 7 Jun 1983
E706\>654. Remove an instance of \<Scan optional space>, since it's now
	redundant. @457
C707. Legalize |\mkern\thinmuskip| and |\mkern5\thinmuskip|. @456
C708. Clean up the treatment of optional spaces in numerical specifications. @455
# A construction like |2.5\space\space\dimen0| was previously
	valid after `|plus|' or `|minus|' only!
# I'm obviously working on Chapter~24 today.
C709\>545. Allow `|\font|' as a \<font identifier> for the current font. @577
C710\>623. Don't make |\gdef| global when $\\{global_defs}<0$. @1218
E711. Produce \\{zero_glue} as the outcome of
	|\advance\spaceskip by-\spaceskip|. @1229
I712. Make |\show| do something appropriate for every possible token. @1294
G713\>559. Replace the (single) |\tokens| parameter by an array of
	256 token registers. @230
C714. Allow |\indent| in math mode; also make |\valign| in math mode produce the
	`|Missing|~|$|' error. @1046,1093
E715. Remove redundant code: There's no need to check \\{cur_group}
	or call \\{off_save} when starting alignments or equation numbers
	in displays. @1130,1142
* 8 Jun 1983
C716. Disallow |\openout-1| and |\closeout-1|. @1350
C717. Disallow |\lastbox| in math mode. @1080
* 9 Jun 1983
I718. Call \\{back_error}, not \\{error}, when |\leaders| aren't followed by
	proper glue. @1078
D719. Initialize for a possible paragraph, after |\noalign|
	in a |\valign|. @785
* 10 Jun 1983
C720\>708. Expand the optional space after an ASCII constant. @442
* 12 Jun 1983
C721. Set $\\{space_factor}\gets1000$ after a rule or a
	constructed accent. @1056,1123
* 14 Jun 1983
D722. Correct a serious blunder: Set $\\{disc_width}\gets0$ before testing
	if $s$ is null (caught by JS). @869
# This is a real bug that existed since the beginning!
	It showed up on page~37 of the
	Version~0 |TRIP| manual, but I didn't notice the problem.
C723\>708. Make optional spaces after \<dimen> like those after \<number>. @448
C724\>568. Insert \\{every_display} before calling \\{build_page}. @1145
I725\>648. Report \TeX's capacity on overflow errors in a way that's
	fully consistent with other statistical reports. @42
* 17 Jun 1983
C726. Make all |\tracing| decisions on the basis of $\ge$ versus $<$,
	not $\ne$ versus~$=$. @581
# Today I finished the draft of Chapter 27 (the last chapter)!
# The changes above were released as Version 0.99 on June 19, 1983.
* 20 Jun 1983
C727. Set |\catcode`\%=14| in |INITEX|. @232
C728\>587. Call \\{normal_paragraph} when |\par| occurs in vertical mode. @1094
# Once again I'm retiring about 8am and awaking about 4pm.
* 21 Jun 1983
C729\>558. Don't append an overfull rule solely because of\/ |\hbadness|. @666
R730. Don't allow the glue-ratio of shrinking to be less than~$-1$. @810,811
* 22 Jun 1983
B731\>653. Declare the parameter to \\{print_roman_int} to be of type \\{integer},
	instead of \\{nonnegative_integer} (found by Debby Clark). @69
C732\>690. Make the keyword `|by|' optional (suggested by LL). @1236
* 24 Jun 1983
I733. Say `|preloaded|' when announcing \\{format_ident}. @1328
* 25 Jun 1983
R734. Add extra boxes and
	glue to the output of alignment. [This thwarts possible attempts
	at trickery by which system-dependent glue set values
	computed by |\span| could have gotten into \TeX's registers by
	things like |\valign| and |\vsplit|. It also has the advantage
	of perfect accuracy in alignment of vertical rules.] @809
C735. Make leaders affect the height or width of the enclosing boxes. @656,671
# Today I'm mainly installing a much-improved format for change files
	in |WEB| programs (suggested by DRF).
* 28 Jun 1983
C736. Permit |\unskip| in vertical mode when we know that it does nothing. @1106
* 1 Jul 1983
E737\>700. Avoid redundant boxes when things like `|{\bf A}|' occur in math. @1186
G738. Add a `|scaled|' feature to |\font| input. @1258
D739\>700. Remember to correct \\{delta} when an accented box changes. @742
* 2 Jul 1983
R740.Introduce \\{bypass_eoln}, to remove anomalous behavior on input files
	of length~1. (Suggested by DRF after the problem was discovered by LL). @31
* 4 Jul 1983
G741. Allow codes like |^^b| as well as |^^B|. @352,355
G742. Introduce new parameters |\escapechar|, |\endlinechar|, |\defaulthyphenchar|,
	and |\defaultskewchar|, to make \TeX\ less dependent on the
	character set. (This affects many modules, since a lot of
	error messages must be broken up so that they use \\{print_esc}.)
* 7 Jul 1983
P743. Use a system-dependent function \\{erstat} when opening or closing
	files (suggested by DRF). @27
* 11 Jul 1983
# The computer is back up after more than 50 hours down time
	(due to air conditioning failure).
I744. Show total glue in the output of\/ |\tracingpages|. @985
R745. Guard against insertion into an hbox. @993
C746. Legalize the assignment \<tokenvar>=\<tokenvar>. @1227
I747. Introduce a new parameter |\errhelp|. @1283
F748\>623. Don't forget to check \\{global_defs} when |\tabskip| is changed. @782
* 12 Jul 1983
C749. Allow an |\outer| macro to appear after |\string|, |\noexpand|,
	and |\meaning| (Todd Allen). @369,471
C750. Make `|\the|' an expandable control sequence (i.e., move it
	from the stomach to the throat); this cleans up
	several annoying glitches. @367
C751\>620. Allow |\unhbox| and |\unhcopy| in math mode if the box is void. @1110
* 13 Jul 1983
# I lectured for four hours at the TUG meeting today after very little sleep!
* 16 Jul 1983
# The following were suggested by TUG meeting discussions.
L752. Round the value of \\{default_rule} more properly: It should be 26215. @463
Q753\>700. Fix |\mathaccent| again; it's still not right!
	The final height should be the maximum of
	the height of accented letter without superscript and
	the height of unaccented letter with superscript.  @742
G754. Add a new feature |\newlinechar|. @59
G755. Allow boxes and rules in discretionaries (suggested by somebody
	from Hewlett-Packard). @1121
I756\>X28. Show all token expansions, not just macros,
	when |\tracingcommands|. @367
C757. Allow |\char| in a |\hyphenation| list. @935
G758. Introduce a new feature |\aftergroup|; it can be implemented with
	\\{save_stack}. @326
C759. Run the running dimensions to alignment boundaries (suggested
	by ARK). @806
* 17 Jul 1983
R760. Zero out \\{hyf} values at the edges, so that
	weird pattern data cannot lead to Pascal range checks. @965
R761\>X190. Decrease the |hc| codes for hyphenation, so that code~127 cannot
	possibly be matched. @937,962
C762\>672. Allow whatsits after hyphenatable words. @899
C763\>604. Represent an italic correction as an explicit kern. @1113
* 18 Jul 1983
C764. Allow lowercase letters in file names. @519
I765. Change the message `|No output file|' to: `|No pages of output|'. @642
I766. Confirm that a quiet mode is being entered, when error
	interaction ends with |Q|, |R|, or |S| (suggested by ARK). @86
# Version 0.999 was finally installed today; a new program listing has
	been printed.
# From now on, I plan to keep all section numbers unchanged.
# I'm done writing Appendix~H; beginning to revise Chapter~20.
* 25 Jul 1983
C767\>663. Allow space after `|to|' in the |\read| command (FY). @1215
# To bed at 1pm today.
* 27 Jul 1983
S768\>665. Stack the current type of\/ |\if|; this precaution is necessary
	in general (FY). @498
# To bed at 2pm today.
* 29 Jul 1983
E769. Avoid putting a control sequence in the hash table
	when it occurs after |\ifx|. (Requested by Math Reviews people.) @507
# Finished a version of {\sl The \TeX book\/} lacking only Appendices
	D, E, and~I, for distribution to interested readers.
# To bed at 10:30pm, planning to arise regularly at 6am for a change.
* 31 Jul 1983
I770\>766. Call \\{update_terminal} when going quiet (HWT). @86
* 1 Aug 1983
C771. Don't put an empty line at the end of an |\input| file! (This simplifies
	the rules and the program, and also gets around a bug that occurred
	at the end of files with $\\{end_line_char}<0$.) @362
# The changes above went into Version 0.9999, which was widely distributed.
* 16 Aug 1983
B772\>665. Rectify a ridiculous gaffe: I initialized $q$ every time the loop
	of \\{change_if_limit} was performed! (Found by FY.) @497
I773\>648. Distinguish `|string|' from `|strings|' when reporting statistics. @1334
A774. Introduce \\{lx}, to correct a bug in |\xleader| computations
	(found by FY). @627
* 20 Aug 1983
F775. Don't forget to apply |\/| to ligatures. @1113
# Today I began to read all previous issues of {\sl TUGboat}, in preparation for
	Appendix~D.
* 27 Aug 1983
I776. Add debugging hack number~16, to help catch subtle data structure bugs. @1339
E777. Remove redundant setting and resetting of \\{name_in_progress}. @531
S778\>618. Suppress |\input| during a font size spec; otherwise
	\\{cur_name} is clobbered (found by MDS). @1258
G779. Introduce new conditionals |\ifhbox| and |\ifvbox|. @505
* 29 Aug 1983
D780\>750. Test for an empty list, if emptiness will mess up the data structure.
	(Found by Todd Allen.) @478
E781\>624. Use \\{fast_store_new_token} in another place for efficiency. @466
I782. Say `|has only|' instead of `|has|'. @579
# These changes yield Version 0.99999, used only at Stanford.
* 30 Aug 1983
C783. Make funny blank spaces showable. @298
* 31 Aug 1983
C784\>754. Make |\newlinechar| affect \\{print_char}, not just \\{print}. @58
* 4 Sep 1983
G785. Add new features |\lastkern|, |\lastpenalty|, |\unkern|, |\unpenalty|.
	@424,996,1105
# OK, Appendix D is finished!!
# The above changes have been installed in Version 0.999999.
* 17 Sep 1983
P786\>548. Don't bother making duplicate font identifiers; that
	was overkill, not really needed. @1258
# Will this be the historic last change to \TeX?
* 18 Sep 1983
I787. Correct a minor inconsistency, `|display|' not `|displayed|'. @211
* 20 Sep 1983
C788\>604. Treat the kerns inserted for accents as explicit kerns. @1125
* 26 Sep 1983
I789. Change `|log|' to `|transcript|' in several messages. @535,1335
# The index was finished today; I mailed the entire {\sl \TeX book\/} to
	Massachusetts for final proofreading before publication.
* 1 Oct 1983
D790. Prevent uninitialized trie positions in case of overflow
	(found by Bernd Schulze). @944
* 7 Oct 1983
# Henceforth our weekly `\TeX\ lunch' meetings will be called `\MF\ lunch'.
# DRF begins to produce {\sl The \TeX book\/} on our APS phototypesetter.
* 14 Oct 1983
P791\>633. Ignore spaces at the ends of lines also in |TEX.POOL| (found
	by DRF). @52
D792\>610. Initialize the \\{history} variable at \\{start_here} (DRF). @1332
* 18 Oct 1983
I793. Extend \\{runaway} to catch runaway text (suggested by FY). @306
D794. Reset \\{cur_cs} after \\{back_input}, not after scanning the
	`|=|' (found by FY). @1226
* 24 Oct 1983
I795\>638. Change the error recovery for bad delimiters, in accordance with
	the changed syntax. (Found by Barry Smith.) @1183
* 9 Nov 1983
E796. Optimize the code a bit more, based on empirical frequency data gathered
	during September and October: In \S45, use the fact that the
	result is almost always true. In \S380, delete `{\bf while}
	\\{true} {\bf do}' since many compilers implement that badly.
	Rewrite \S852 to avoid calling \\{badness} in the most common case.
	@45,380,852
* 3 Dec 1983
F797. Don't forget to call |error| after the message has been
	given (noticed by Gabi Kuper). @500
# Version 1.0 released today incorporates all of the above.
* 9 Dec 1983
# Dinner party with 36 guests to celebrate \TeX's coming of age.
* 2 Feb 1984
S798\>786. Reinstall |\font| precautions that I thought were unnecessary.
	I overlooked many problematic possibilities, like
	`|{\font\a=x| |\global\a}| |\the\font|'
	and `|\font\a=x| |\font\b=x| |\let\b=\undefined| |\the\a|', etc.
	(Found by Mike Urban.) The new remedy involves removal of the
	\\{font_ident} array and putting the identifiers into a frozen
	part of the hash table; so there's a sprinkling of corrections
	in lots of modules. But basically the change is quite conservative,
	so it shouldn't spawn any new bugs (it says here). @222,267,1257
* 9 Feb 1984
S799. Remove the possibility of double interrupt, in a scenario
	found by Clint Cuzzo. @1031
* 12 Feb 1984
Q800. Improve spacing in a formula like |$(A,<)$|. @764
* 13 Feb 1984
A801. Avoid a bad {\bf goto}, as diagnosed by Clint Cuzzo and George O'Connor.
	(Must not go directly to \\{switch}.) @346
E802. Conserve string pool space by not storing file name in two
	guises (suggested by DRF). @537
* 26 Feb 1984
I803. Make scaled output look cleaner by printing fewer decimals whenever
	this involves no loss of accuracy. (Suggested by \MF\ development.) @103
* 2 Mar 1984
R804. Maintain 17-digit accuracy, not 16; now
	constants like `|.00000762939453126pt|' will round correctly. @452
* 16 Mar 1984
R805. Plug a loophole that permitted recursion in \\{get_next}, by disallowing
	deletions in \\{check_outer_validity}. @336
* 24 Mar 1984
I806. Open the terminal before trying to wake it up, when the program starts bad.
	@1332
* 27 Mar 1984
R807. Check that $k<63$, to avoid the
	|\patterns{xxx...xxxdxxxdxxx}| anomaly found by Jacques D\'esarm\'enien. @962
* 11 Apr 1984
F808. Supply code for the missing case \\{adjust_node} in \\{copy_node_list}. @206
# Yoicks, how could serious bugs like that have escaped detection?
* 11 Jun 1984
D809\>627. Initialize \\{char_base}, etc., for \\{null_font}.
	(Found by Nick Briggs.) @552
R810. Clear the \\{buffer} array initially (Briggs). @331
* 21 Jun 1984
C811. Look ahead for ligature or kern after a |\chardef|'d item
	(D\'esarm\'enien). @1038
* 4 Jul 1984
R812. Make the quarterword constraint explicit with a
	new `\\{bad}' case (19). @111
* 7 Jul 1984
E813. Optimize \\{firm_up_the_line} slightly,
	to be consistent with the \MF\ program. @363
* 8 Jul 1984
I814. Give additional diagnostics when |\tracingmacros>1|. @323
# The changes above were incorporated in Version 1.1, released July 9, 1984.
* 27 Jul 1984
I815. Say `|see| |the| |transcript| |file|' after handling offline |\show|
	commands. (Suggested by \MF.) @1298
* 20 Oct 1984
I816. Allow `|0|' in response to error prompts. @84
# Those two changes led to Version 1.2.
* 25 Nov 1984
R817. Don't forget to check for \\{null} before looking at subfields
	of a node. (This was ``dirty Pascal,'' with two quarterword 0's
	read as a halfword.) @846
R818. Ditto in another place! @939
E819. Remove the fixed-at-compile-time
	partition between lower and upper memory. @116,125,162
# This major change in memory management
	completes Version 1.3, which was published in preliminary
	looseleaf form as `\TeX: The Program'.
* 20 Dec 1984
R820. Keep the \\{node_size} field from overflowing if the lower part of memory
	is too large. @125
# That was another bug in existence from the beginning!
* 5 Jan 1985
I821. Improve the missing-format-file error (DRF). @524
* 7 Jan 1985
I822. Update the terminal right away so that the welcoming message will
	appear as soon as possible (DRF). @61
* 23 Jan 1985
I823. Convey more uncertainty in the
	help message at times of \\{confusion}. @95
I824\>610. Improve the \\{history} logic in the \\{warning_issued} case. @245
* 18 Feb 1985
P825\>810. Stick to standard Pascal: Don't
	use \\{first} in a {\bf for} loop. [Some procedures ``threaten'' it
	globally, according to British Standard 6192, section 6.8.3.9.]
	(Pointed out by CET.) @331
* 11 Apr 1985
S826. Prevent nonexistent characters from being output by
	unusual combinations of ligatures and hyphenation. @915
* 15 Apr 1985
L827\>819. Compute memory usage correctly in |INITEX|; the previous number
	was wrong because of a |WEB| text macro without parentheses (DRF). @164
* 16 Apr 1985
E828. Speed up \\{flush_list} by not calling \\{free_avail} (DRF). @123
* 17 Apr 1985
A829\>788. Introduce a special kind of kern for accent positioning;
	it must not disappear after a line break. @837,879,1125
* 18 Apr 1985
R830\>755. Prevent |\lastbox| and |\unkern| from removing discretionary replacements.
	@1081,1105
# That completes Version 1.4.
* 26 Apr 1985
C831. Don't try \\{\TeX_area} if a nonstandard file area has been specified
	(DRF). @537
# That was \#401 in \TeX78; I never learn!
* 30 Apr 1985
C832\>754. Eliminate the limitation on |\write| length; the reason for it
	has disappeared (Nancy Tuma). @1370
* 8 May 1985
D833\>819. Allocate two words for the head of the \\{active} list (CET). @162
* 11 May 1985
I834. Change \\{wterm} to \\{wterm_ln} after a bad beginning (Bill Gropp). @1332
E835\>806. Don't open the terminal twice (CET). @1332
* 22 May 1985
R836. Test for \\{batch_mode} after trying to open the transcript file,
	not before (DRF). @92
R837. Be prepared for string pool overflow while reading the command line!
	(This bug was first found in \MF, when it could occur more easily.) @525
* 7 Aug 1985
A838. Fix a bug in |\edef\foo{\iffalse\fi\the\toks0}|: \TeX\ should stay in the
	loop when expanding non-|\the|. (Found by Dan Brotsky.) @478
# The above changes were incorporated in Version 1.5.
* 27 Nov 1985
C839\>764. Make `|plain|' a lowercase name, for consistency with the manual. @521
I840\>669. Wake up the terminal for |\show| commands. @1294,1297
# The above changes were incorporated in Version 2.0, which was published
	as Volume~B of the {\sl Computers \& Typesetting\/} series.
* 15 Dec 1986
I841. Punctuate the Poirot help message more carefully. @1283
* 28 Jan 1987
R842. Make sure that \\{max_in_open} doesn't exceed 127 (DRF). @14
D843\>680. Don't allow a |\kern| to be clobbered at the end of a pre-break list
	when a discretionary break is taken. (A missing `{\bf else}' was the
	source of the error, diagnosed incorrectly before.) @881
D844. Take account of discarded nodes when computing the background width
	after a discretionary. @840
# That was the first really serious bug detected for more than 17 months! I found it
	while experimenting with right-to-left extensions.
# Version 2.1 was released on January 26, 1987.
* 5 Feb 1987
E845. Remove cases in \\{shorthand_def} that cannot occur (found by Pat Monardo). @1224
* 14 Apr 1987
R846. Improve robustness of data structure display
	when debugging (Ronaldo Am\'a). @174,182
* 21 Apr 1987
E847. Make the storage allocation algorithm more elegant and efficient. @127
* 22 Apr 1987
A848\>742. Calculate the empty-line condition properly when \\{end_line_char} is
	absent. @360
# The previous three changes were found while I was teaching a class based
	on Volume~B; they led to Version 2.2.
* 28 Apr 1987
E849. Avoid closing a file when \TeX\ knows that it isn't open (JS). @560
* 3 Aug 1987
S850. Clean up unfinished output if it's necessary to
	\\{jump_out} (Klaus Gunterman). @642
# That makes Version 2.3; subsequent version numbers won't be logged here.
* 19 Aug 1987
A851. Indent rules properly in cases like\hfil\break
	|\hangindent=1pt$$\halign{...\cr\noalign{\hrule}}$$|. @806
* 20 Aug 1987
S852. Introduce \\{co_backup} because of cases like
	|\hskip 0pt plus 1fil\ifdim| (Alan Guth). @366
* 9 Nov 1987
S853. Change the calculation for number of leader boxes, so that
	it won't be too sensitive to roundoff error near exact multiples
	(M. F. Bridgland). @626
* 17 Nov 1987
A854. Replace my stupid algorithm
	for fixed-point multiplication of negatives (WGS). @572
* 12 Dec 1987
B855. Fix a typo in the initialization of hyphenation tables  (PB). @952
# That error was almost completely harmless, thus undetectable,
	except if some |\lccode| is~1 and no |\patterns| are given.
* 23 Dec 1987
S856\>564. Be more cautious when ``relaxing'' a previously undefined |\csname|;
	you might be inside a group (CET). @372
* 20 Apr 1988
S857. Make sure \\{temp_head} is well-formed whenever it can be
	printed in a ``runaway'' message: Consider constructions like
	|\outer\def\a0{}\a\a| (Silvio Levy). @391
* 24 Apr 1988
S858\>618. Avoid conflicting use of the string pool in constructions like
	|\def\\#1{}\input a\\\z| (Robert Messer). @260
* 10 May 1988
R859. Amend the |\patterns| data structure when $\\{trie_min}=0$
	(PB). @951,953
* 25 May 1988
R860. Guarantee that \\{trie_pointer} cannot be out of range. @923
S861\>618. Avoid additional bugs like \#858 in constructions
	like |\input a\romannumeral1|, etc. @464,465,470
R862\>618. Prevent similar string pool confusion that could occur
	during the processing of |**\input\romannumeral6|. @525
* 19 Jun 1988
S863\>819. Prevent a negative dividend from rounding upward,
	causing a loop (CET). @126
E864\>819. Adopt a smoother allocation strategy when
	memory is nearly gone (CET). @126
* 20 Jun 1988
D865\>852. Initialize \\{cur_order}, now that it's being backed up
	(Tsunetoshi Hayashi). @439
* 6 Nov 1988
S866\>612. Disable \\{fatal_error} in \\{prompt_input}, so that
	\\{open_log_file} can use it safely (Tim Morgan). @71
S867\>836. Force terminal output whenever \\{open_log_file} fails. @535
* 14 Dec 1988
P868\>866. Restore \\{fatal_error} in \\{prompt_input}, but don't
	let it be unsafe for \\{open_log_file}. @92,534
* 23 Jan 1989
D869. Give $q$ a legal value when recovering from ``infinite shrinkage''
	error. @976,1004
* 17 Feb 1989
D870\>758. Avoid spurious error message for |\aftergroup\relax\dump| by avoiding
	inaccessible |\aftergroup| tokens (FM and Rainer Sch\"opf). @280
* 20 Mar 1989
R871. Don't refer to \\{link}(\\{null}) even when it ``can't happen''
	(PB). @791
* 7 Jun 1989
S872. Avoid confusion from |$$\begingroup\halign{#\cr}$$| (FM). @1130
* 20 Jun 1989
S873. Put fraction digits into dynamic memory, not the global \\{dig} array,
	because of constructions like |.5\ifdim.6| (FM). @452
* 17 Jul 1989
S874. Prevent embarrassing attempts to report errors before the string
	mechanism has been fully initialized, for example when the
	command line exceeds the buffer size (WGS). @31
* 16 Aug 1989
M875. Allow integer products to be 31 bits long (FM). @105
* 31 Aug 1989
C876\>441. Increase the number of tokens shown by \\{token_show}
	(J. Lavagnino). @295
S877. Avoid confusion from |$$\begingroup\eqno$$| (FM). @1140
# The recent TUG meeting turned out to be an extend-\TeX-for-the-nineties
	party! I agreed that some extensions for non-English languages
	ought to be made while I still knew how to do them. (In other words,
	I broke my firm commitment to keeping \TeX\ completely stable;
	but in this case nobody objected.) The following eleven changes
	were coded during the month of September.
* 30 Sep 1989
G878. Install major change allowing general 8-bit code input. @38,352
G879. Install major change allowing multiple hyphenation tables
	(M. Ferguson). @923
G880. Introduce new parameters |\lefthyphenmin| and |\righthyphenmin|. @923
G881. Introduce major new ligature capabilities including implicit
	boundary characters. @908,1037
G882. Install new |\inputlineno| feature suggested by MDS. @424
G883. Install new |\holdinginserts| feature suggested by FM. @1014
G884. Install new |\badness| feature. @424,664
G885. Install new |\emergencystretch| feature. @863
G886. Install new |\errorcontextlines| feature suggested by FM. @311
S887. Recover from anomaly when hyphenation |char_warning| clobbers
	|old_setting|. @863
P888. Make it easier to change the format extension (Don Hosek). @520,1328
* 16 Oct 1989
R889. Avoid range check in null font with |bc=256| (PB). @565
* 22 Nov 1989
S890\>856. Prevent \\{save_stack} conflicts in
	|{\hbox\expandafter{\csname\endcsname}}| and\kern-3pt\break
	similar constructions (WGS). @645,1117
S891\>858. System-dependent parts of file names must be addressed relatively,
	not absolutely (FM and Rainer Sch\"opf). @516,517
* 3 Dec 1989
G892\>880. Allow different hyphenmins in the same paragraph (M. Ferguson). @1376
S893. Distinguish |\par| from characters on |\if| tests. (MVL). @334
S894\>378. Alignments need to be more robust against malicious
	attacks (MVL). @782
C895. Don't let kerns in discretionaries disappear at breaks (MVL). @869
Q896\>881. Make the new hyphenation reconstruction procedure less cautious,
	so that it doesn't lose hyphens found by the old method. @914
* 11 Dec 1989
D897\>879. Make an undumped trie dumpable again (PB). @1325
* 18 Dec 1989
G898\>588. Allow access to page totals in |\output| routines
	(FM and Chris Rowley). @421
* 22 Jan 1990
R899\>611. Recognize more cases of unbalanced |\output| (CET). @1026
* 29 Jan 1990
S900\>758. Make |\aftergroup| work properly after |\eqno| (Michael Downes).
	@1194
* 1 Feb 1990
S901\>878. Fix one more case of \\{end_line_char_inactive} (WGS). @360
* 22 Feb 1990
R902. Don't lose the last active node when total demerits are very high (FM).
	@836,854
* 13 Mar 1990
D903. Doublecheck math fonts after making equation number (MVL). @1194
D904. Don't forget to rule out charnodes before testing \\{type} (MVL).
	@805,1202
* 23 Mar 1990
F905\>881. Don't change the font of punctuation preceding a hyphenated word
	(Scott C. Allendorf). @903
I906. Balance the parentheses shown on the terminal during normal runs. @1335
E907. Optimize |\ifx\p\q| after |\let\p=\q| (MVL). @508
S908. Treat migration properly in displays (MVL). @1199,1205
# We're now up to Version 3.0; I sincerely hope all bugs have been found.
* 11 May 1990
F909\>881. Initialize |\nullfont| ligature parameters (Lance Carnes). @552
* 22 July 1990
S910\>579. Treat |\prevgraf| as zero within |\write| (Bogus\l aw Jackowski).
	@422
* 26 July 1990
S911. Report `|l.1|' when first line of file overflows buffer
	(George Russell). @538
* 5 December 1990
S912\>878. Translate unprintable characters in font identifiers (WGS). @63
* 28 December 1990
R913. Avoid range check when there are 65536 or more pages (Eberhard Mattes).
	@642
* 20 September 1991
I914\>878. Improve error message for |\mathchar| out of range. @436
S915\>878. Retain unprintable internal strings in 8-bit form (FM). @59
S916\>881. Retain right punctuation context for ligature reconstruction
	(problem found by Brian Hamilton Kelly). @903
* 10 January 1992
S917\>881. Also avoid producing a double kern at boundary (CET). @897
S918. Disallow |\setbox| where it doesn't work (Robert Hunt). @1241,1270
S919. Robustify |\mskip| and |\mkern| in presence of negative quad (WGS).
	@716,717
S920\>679. Defend against `|}{|' in |\read| (Michael Downes). @483
E921\>798. Save string memory if font occurs repeatedly (Bogus\l aw Jackowski).
	@1260
S922\>784. Don't let |\newlinechar| interrupt unprintable expansion (Bernd
	Raichle). @59,60
* 7 February 1992
D923\>881. Restore |cur_l| properly when boundary character doesn't exist
	(Mattes and Raichle). @1036
* 17 July 1992
C924\>892. Use current language at beginning of horizontal mode (Rainer
	Sch\"opf and CET). @1091,1200
* 17 December 1992
R925\>879. Avoid (harmless) range errors (Philip Taylor and CET). @934,960
* 25 February 1993
C926\>881. Protect kerns inserted by boundary characters (William Baxter).
	@837,866
S927\>917. Don't let boundary kern disappear after hyphenation. @897
* 26 June 1993
R928\>668. Avoid potential future bug (Peter Breitenlohner). @628,637
* 17 December 1993
S929\>881. Boundary character representation shouldn't depend on the font
	memory size (Berthold Horn). @549,1323
* 10 March 1994
R930. Huge font parameter number may exceed array bound (CET). @549
* 4 September 1994
F931\>926. Math kerns are explicit (Walter Carlip). @717
R932. Avoid overflow on huge real-to-integer conversion. @625,634
* 19 March 1995
R933. Avoid spurious reference counts in format files (PB). @1335
* 23 November 1998
R934. Make sure that TeX is certifiably Y2K-safe. @1328
* 12 July 1999
A935\>255. |\xleaders| often drops the final box (Hiroshi Nakashima). @627,636
* 30 August 2001
R936. Don't allow a million unbalanced braces followed by |\cr|
	outside of any alignment (Ralf Roth). @789
R937. Don't allow end-template except at end of template (Roth). @325,1131
* 30 September 2002
Q938. Improve rounding of glue during output (M. F. Bridgland). @625,634
* 18 March 2008
F939. Forgot to goto the proper error recovery (DRF). @395
E940. Avoid a case of dirty Pascal and speed up inner loop. @1035
R941. Forget reference to last_glue in format file (DRF). @1335
R942. Glue reference not updated after overflow error (DRF). @1236
B943. Muglue in \leaders had wrong units; now disallowed (DRF). @1078
E944. Speedup of ligatures and kerns at end of a word (DRF). @1039
R945. Another sanity check of TFM files for security (DRF). @365
I946. Give better size data for unmagnified insertions. @986
* 6 January 2014
C947. Space after \csname\endcsname to match other spaces. (Oleg Bulatov) @262
\relax
\bye

Up to a point it is better to let the snags [bugs] be there
than to spend such time in design that there are none
(how many decades would this course take?).
-- A M Turing
   Proposals for Development in the Mathematics Division
     of an Automatic Computing Engine (ACE)
   Report E882, Executive Committee, National Physical Laboratory (NPL)
   1945; reprinted in April 1972 as NPL report Com Sci 57
   page 18
   quoted by Carpenter and Doran in The Computer Journal 20 (1977), 273.

DRF David Fuchs
HWT Howard Trickey
FY  Frank Yellin
LL  Leslie Lamport
JS  Jim Sterken
ARK Arthur Keller
CET Chris Thompson
FM  Frank Mittelbach (added subsequent to publication of paper)
PB  Peter Breitenlohner (ditto)
WGS Wayne G. Sullivan (ditto)
MVL Marc van Leeuwen (ditto)
MDS Michael D. Spivak (ditto)