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-rw-r--r--info/impatient/concepts.tex26
1 files changed, 14 insertions, 12 deletions
diff --git a/info/impatient/concepts.tex b/info/impatient/concepts.tex
index 2b38675345..ac53a01990 100644
--- a/info/impatient/concepts.tex
+++ b/info/impatient/concepts.tex
@@ -1,5 +1,6 @@
+% $Id: concepts.tex,v 1.5 2020/01/01 23:55:26 karl Exp $
% This is part of the book TeX for the Impatient.
-% Copyright (C) 2003, 2014 Paul W. Abrahams, Kathryn A. Hargreaves, Karl Berry.
+% Copyright (C) 2003-2020 Paul W. Abrahams, Kathryn A. Hargreaves, Karl Berry.
% See file fdl.tex for copying conditions.
\input macros
@@ -755,7 +756,7 @@ is an instruction to \TeX\ to produce a certain character in a certain
(the usual escape character) is $92$. If
you type `|\char92 grok|', it is \emph{not} equivalent to |\grok|.
Instead it tells \TeX\ to
-typeset `$c$grok', where $c$ is the character in position $92$
+typeset `$c$\kern.075em grok', where $c$ is the character in position $92$
of the code table for the current font.
You can use the ^|\catcode| command \ctsref{\catcode} to reassign the
@@ -765,10 +766,11 @@ change the roles of various characters. For instance, if you type
to ``letter''. You then can use `|@|' in the name of a control
sequence.
-Here is a list of the category codes as they're defined in
-\refterm{\plainTeX} (see \xref{twocarets} for an explanation of
+Here is a list of the category codes defined by \TeX,
+(see \xref{twocarets} for an explanation of
the |^^| notation),
-together with the characters in each category:
+together with the characters in each category (as assigned
+by \TeX\ and \refterm{\plainTeX}):
\xrdef{catcodes}
\vskip\abovedisplayskip
@@ -841,8 +843,7 @@ is a valid group, and so are \hbox{`|[a b}|'} and~\hbox{`|{a b]|'}.
The characters in categories $11$ (letter) and $12$
(other character) act as \refterm{commands:command}
that mean
-``produce a \refterm{box} containing this character
-typeset in the current font''.
+``typeset the character with this code from the current font''.
The only distinction between letters and ``other'' characters is
that letters can appear in \refterm{control word}s but
``other'' characters~can't.
@@ -874,7 +875,7 @@ code until its \emph{second} look at the character. For example:
\csdisplay
\def\foo{\catcode`\$ = 11 }% Make $ be a letter.
\foo$ % Produces a `$'.
-\foo$ % Undefined control sequence `foo$'.
+\foo$ % Undefined control sequence `\foo$'.
|
\noindent
This bit of \TeX\ code produces `\$' in the typeset output. When
@@ -968,11 +969,12 @@ notation you'll find it handy to have a table of \ascii\ codes.
An output character is a character to be typeset.
A command for producing an output character has the meaning
-``Produce a \refterm{box} containing
+``Typeset
character number $n$ from the current \refterm{font}'',
where $n$ is determined by the command.
-\TeX\ produces your typeset document by combining such boxes with
-other typographical \hbox{elements} and arranging them
+\TeX\ produces your typeset document by combining such characters
+with
+other typographical \hbox{elements} in boxes, and arranging them
on the page.
An input character whose category code is $11$ (^{letter}) or $12$ (other)
@@ -992,7 +994,7 @@ command `|\char |$n$' \ctsref{\char}, ^^|\char| where $n$ is a
The \defterm{class} of a \refterm{character} specifies that character's
role in math formulas. The class of a character is encoded in its
\refterm{mathcode}. ^^{mathcodes//class encoded in} For example, the
-equals sign `|=|' is in class $3$ (Relation). \TeX\ uses its knowledge
+equals sign `|=|' has class $3$ (Relation). \TeX\ uses its knowledge
of character classes to decide how much space to put between different
components of a math formula. \margin{clarifying material added} For
example, here's a math formula shown first as \TeX\ normally prints it