summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/doc/latex/stackengine/stackengine.tex
blob: f11d23b691d4955a330a30928af898f63090c542 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
\documentclass{article}
\usepackage{scalerel}
\usepackage{stackengine}
\usepackage{verbatimbox}
\usepackage{boxhandler}
\parindent 0in\parskip 1em
\newlength\dotscale

\setlength{\dotscale}{.4ex}         % DOTSIZE<---CAN CHANGE THESE
\def\newdot{\scalerel*{.}{\rule[-\dotscale]{1ex}{\dotscale}}}
\def\newdot{\scalerel*{.}{\rule{1ex}{\dotscale}}}

% FOR CLOSE-BOXING ARGUMENTS
\fboxsep=0pt\fboxrule=.6pt

\def\rl{\protect\rule[-.3pt]{2ex}{.6pt}}
\def\ste{\textsf{stackengine}}
\def\bs{\texttt{\char'134}}
\let\vb\verb
\reversemarginpar
\marginparwidth 1.6in
\newcommand\margtt[1]{\marginpar{\hfill\ttfamily#1}}
\newcommand\margcmd[1]{\marginpar{\hfill\ttfamily\char'134#1}}
\newcommand\cmd[1]{\texttt{\char'134#1}}
\def\lapmark{\rule[-.3\baselineskip]{.1ex}{\baselineskip}}
\def\blmark{\rl\stackengine{-.9ex}{B}{\rule{.35ex}{0pt}L}{U}{l}{F}{T}{S}\rl}

\begin{document}

\begin{center}
\LARGE The {\ste} Package\\
\rule{0em}{.7em}\small Highly customized stacking of objects, insets,
baseline changes, \textit{etc.}\\
\rule{0em}{2.7em}\large Steven B. Segletes\\
steven.b.segletes.civ@mail.mil\\
\rule{0em}{1.7em}\today\\
\stackengineversionnumber
\end{center}

%\tableofcontents

\sffamily%
Note: A syntax change in version 2.0 may require minor changes in your
existing V1.0 stackengine code.  See section~\ref{s:bc} for details.
\rmfamily%

\section{Definitions and Terms}

Before I describe the various commands of this package, it is best for
you to familiarize yourself with a few terms as used in this package.

\subsection{Short Stacks and Long Stacks\label{s:st}}
\def\usestackstrut{T}
\def\stacktype{L}
\Huge\setstackgap{S}{.4ex}
\setstackgap{L}{2.2ex}\normalsize 

In this package, ``Short'' refers to squeezing the extra space out of
glyphs comprising the stack, so that the inter-item gap is solely what
is set.  Likewise, ``Long'' refers to a stack kept at constant
inter-item baseline spacing.  Let's look at the following two
examples to see this clearly.

Notice the consistent inter-item gap on a short stack: 
\Huge
\Shortstack{{\fbox{t}} {\fbox{y}} {\fbox{k}} {\fbox{e}}}
%\Shortstack{{\fbox{a}} {\fbox{h}} {\fbox{g}} {\fbox{b}}}
\normalsize

Notice the consistent inter-baseline spacing on a long stack: 
\Huge
\Longstack{{{\rl t}} {{\rl y}} {{\rl k}} {{\rl e}}}
%\Longstack{{{\rl a}} {{\rl h}} {{\rl g}} {{\rl b}}}
\normalsize

In this package, the default spacing (\textit{i.e.}, stacklength) for
the long stack, saved in the length \vb|\Lstackgap| is the value
\vb|\baselineskip|.  For short stacks, the default stacklength, stored in
\vb|\Sstackgap|, is 3pt, which corresponds to the same spacing found in
\TeX's \vb|\shortstack| command.  The default stack type constructed by
this package is short, denoted by the definition of \vb|\stacktype| as
``S'' (as opposed to ``L'' for long stacks).  These defaults can be
changed.

\subsection{Baseline}
\setstackgap{L}{.8\baselineskip}
\setstackgap{S}{4pt}

The baseline is the horizontal line on which the current (unstacked)
text is set.  For non-descending letters, the bottom of the letters sit
upon the baseline.  In this document, we will graphically use the symbol
{\blmark} to denote the current baseline of the text, as in

\blmark\rl\Shortunderstack{A B C}\rl\rl text continues here

\subsection{(Over)Stacks and Understacks}

\setstackgap{L}{.8\baselineskip}
\setstackgap{S}{4pt}
In general terms, a stack is built up from the baseline, while an
understack is built down from the baseline.  

So, for example,
\Longstack{a b c}
is a stack, while
\Longunderstack{a b c}
is an understack.

With this package, both stacks and understacks can be long or short,
depending on how the invocation is made.  Sometimes, in this
documentation, a stack will be called an ``overstack'' in order to avoid
confusion with ``understack.''

\subsection{Anchors}

The term ``anchor'' is used to denote an item in the stack whose
baseline does not change in the course of the stacking operation.  In
essence, stacking is done relative to the anchor.

For example, in \Shortstack{a b c}, the letter ``c'' is the anchor.  

In the understack \Shortunderstack{a b c}, ``a'' is the anchor.

\subsection{Alignment\label{s:sal}}

Anyone familiar with \LaTeX{} knows something about the horizontal
alignment settings ``l'', ``c'' and ``r''.  As pertains to a stack, we
refer to the alignment of the various rows of the stack, as shown in the
following examples.

\setstackgap{S}{3pt}\setstackgap{L}{12pt}%

{\centering
Left: \Shortstack[l]{abcd abc ab a}~~
Center: \Shortstack[c]{abcd abc ab a}~~
Right: \Shortstack[r]{abcd abc ab a}

}
The default alignment within a stack may be set with the
\vb|\stackalignment| definition, to possible values of \vb|l|,
\vb|c|, or \vb|r|, denoting left, center, and right alignments,
respectively.  In addition, a number of the stacking macros provide the
alignment as an argument or optional argument that can be specified at
time of invocation.

The {\ste} package defaults to center alignment, unless reset by way of
the \vb|\stackalignment| definition.


\section{Defaults and Macros Provided by \ste}


\subsection{Defaults and How to Set Them}

There are several macros that serve to store package default
definitions.  When a macro does NOT explicitly ask for one of the
quantities defined by these defaults, it will use the values of these
parameters to serve as the default value.  However, some stacking macros
may ask the user to specify an explicit value for any number of these
parameters in the calling arguments.  In that case, an explicit value
may be provided or else the variable holding the default value may
itself be provided as the argument.

Let us first consider the stackgap defaults, associated with short and
long stacks.  Those stackgaps are actually stored in the \verb|\def|'s

\vb|\Sstackgap|\\
\vb|\Lstackgap|

The parameter \vb|\Sstackgap| is the default inter-item gap for any
stacking command that builds a short stack.  It defaults to 3pt.
Correspondingly, \vb|\Lstackgap| is the inter-item baselineskip for
any stacking command that builds a long stack.  It defaults to
\vb|\baselineskip|.  To change these defaults, the following macro is
provided:

\itshape
\vb|\setstackgap{S}{|inter-item stackgap\verb|}|\\
\vb|\setstackgap{L}{|inter-item baselineskip\verb|}|
\upshape

In addition, there is another macro, which may be invoked by the user:

\vb|\stackgap|

The macro \vb|\stackgap| will look at the current value of
\vb|\stacktype| and will output either \vb|\Sstackgap| or
\vb|\LStackgap|, depending on whether \vb|\stacktype| is defined as
``S'' (short) or ``L'' (long).

In addition to these lengths, there are several parameter definitions
that define default behaviors for those stacking macros when explict
values of these settings are not requested.  The parameters, each set
with a \vb|\def| command, are

\itshape
\vb|\def\stackalignment{l| or \vb|c| or \vb|r}|\\
\vb|\def\quietstack{T| or \vb|F}|\\
\vb|\def\useanchorwidth{T| or \vb|F}|\\
\vb|\def\stacktype{S| or \vb|L}|\\
\vb|\def\usestackstrut{T| or \vb|F}|
\upshape

The parameter \vb|\stackalignment| defaults to ``c'' (center) and
defines the default stacking alignment.  Other options include ``l''
(left) and ``r'' (right).  See \S\ref{s:sal} for more discussion
of this parameter.

The parameter \vb|\quietstack| defaults to ``F'' (false) and
determines whether the result of a stacking operation is supressed from
the output.  If the output is suppressed by setting this parameter to
``T'', the most recent stacking operation may be recovered with a
\vb|\usebox{\stackedbox}|.  See \S\ref{s:qs} for more
discussion of this parameter.

The parameter \vb|\useanchorwidth| defaults to ``F'' (false) and
indicates that, upon creation, the stack width should be taken as the
widest element of the stack.  When set to ``T'', the stack width, upon
creation, is instead taken as the width of the anchor.  Note that this
parameter applies at the time of stack creation and cannot be used to
retroactively change the characteristics of an existing stack.  See
\S\ref{s:uaw} for more discussion of this parameter.

The parameter \vb|\stacktype| defaults to ``S'' (short stack) and
defines the default type of stack to build.  When set to ``L'', newly
created stacks are, by default, long stacks.  Refer to
\S\ref{s:st} for a definition of these terms.

The parameter \vb|\usestackstrut| defaults to ``T'' (true) and has
limited application.  It only comes into play when using
\vb|\stackanchor| with \vb|\stacktype| ``S''.  It is described in
more detail in \S\ref{s:sa}.

For macros which require explicit specification of some of these
parameters, the parameter token itself (\textit{e.g.},
\cmd{stackalignment}, \cmd{quietstack}, \textit{etc.}) may be provided
as the argument, if the default behavior is desired.

\subsection{Stacking Macros}

\subsubsection{\cmd{stackengine}}

The basic (and most general) stacking macro provided by this package is
\vb|\stackengine|.  Nearly all other macros of this package merely
provide an abbreviated invocation form of this macro, tailored for a
particular application.  The syntax is:

\itshape
\vb|\stackengine{\Sstackgap| or
  \vb|\Lstackgap| or
  \vb|\stackgap| or stacklength%
  \vb|}|\\
\vb|            {|anchor\vb|}|\\
\vb|            {|item\vb|}|\\
\vb|            {O| or \vb|U}|\\
\vb|            {\stackalignment| or
  \vb|l| or
  \vb|c| or
  \vb|r}|\\
\vb|            {\quietstack| or \vb|T| or \vb|F}|\\
\vb|            {\useanchorwidth| or \vb|T| or \vb|F}|\\
\vb|            {\stacktype| or \vb|S| or \vb|L}|
\upshape

There are no optional arguments with \vb|\stackengine|.  The first
item is a stacking length, which can mean different things depending on
whether a short- or long-stack is being created, as discussed in
\S\ref{s:st}.  The second argument is the stack anchor, whose
baseline does not change.  The third argument is the item stacked
relative to the anchor.  The fourth argument is either an ``O'' (for a
normal or overstack) or a ``U'' (for an understack).  The fifth argument
denotes a left, center, or right alignment of the stack items with the
use of ``l'', ``c'', or ``r''.  The sixth argument is either a ``T'' or
``F'' to denote whether the resulting stack is NOT printed (``T''
denotes ``do NOT print'').  The seventh argument, also a ``T'' or an
``F'', denotes when ``T'' that the width of the whole stack is to be
taken as the width of the anchor.  Otherwise, the width of the stack
conforms to the width of the widest item in the stack.  The final
argument is defined as either an ``S'' or an ``L'' to denote whether a
short stack or a long stack is being requested.

While none of the arguments to \vb|\stackengine| have default values,
there are various definitions in the package that store default values.
When one wishes a stack to possess certain default properties, these
default definitions may be passed as the values for the respective
arguments to \vb|\stackengine|.  Arguments 1, 5, 6, 7, and 8 each
possess a corresponding parameter containing the default variable.  So,
for example,

\begin{verbatim}
\stackengine{\stackgap}{A}{BC}{O}{\stackalignment}
            {\quietstack}{\useanchorwidth}{\stacktype}
\end{verbatim}

will stack the letters ``BC'' over ``A'' using the default values of
\vb|\stackalignment|, \vb|\quietstack|, \vb|\useanchorwidth|,
and \vb|\stacktype|.  In addition, the stackgap will be set to
\vb|\Sstackgap| if \vb|\stacktype| is ``S'' or to \vb|\Lstackgap|
if \vb|\stacktype| is ``L''.  Alternately, the  same stack could be 
forced to be a long stack with right-alignment and be typeset using

\begin{verbatim}
\stackengine{\Lstackgap}{A}{BC}{O}{r}{F}{\useanchorwidth}{L}
\end{verbatim}

\subsubsection{\cmd{stackon} and \cmd{stackunder}}

The \vb|\stackon| and \vb|\stackunder| macros are abbreviated forms
of \vb|\stackengine| in which the default values of parameters are
taken.  The only exception is the stacklength, which may be provided as
an optional argument.

\itshape
\vb|\stackon[|stacklength%
  \vb|]{|anchor%
  \vb|}{|item
  \vb|}|\\
\vb|\stackunder[|stacklength%
  \vb|]{|anchor%
  \vb|}{|item
  \vb|}|
\upshape

In the case of \vb|\stackon|, an (over)stack is created, whereas an
understack is created with \vb|\stackunder|.  With both of these
commands, the anchor is the first mandatory argument, and the item to be
stacked above or below it is the second mandatory argument.

\subsubsection{\cmd{Shortstack} and \cmd{Longstack}\label{s:sls}}

The \vb|\Shortstack| and \vb|\Longstack| commands are stacking
commands that allow more than two stacking rows to be specified at once.
The items of a stack are provided in a space-separated list, as follows:

\itshape
\vb|\Shortstack[|alignment%
  \vb|]{|item %
  \vb|{|it em%
  \vb|} {\|item%
  \vb|} $|item%
  \vb|$| ... anchor%
  \vb|}|\\
\vb|\Longstack[|alignment%
  \vb|]{|item %
  \vb|{|it em%
  \vb|} {\|item%
  \vb|} $|item%
  \vb|$| ... anchor%
  \vb|}|
\upshape

The first item is at the top of the stack, farthest from the baseline,
while the last item is the anchor of the stack.  If an item (the
contents of a single row) contains spaces, enclose the item in braces.
If the item ends with a macro, enclose the item in braces.  While not
particularly intended for math mode (see \S\ref{s:mm} for more
details), math items may be enclosed within dollar-sign delimiters.
\bfseries Note that, because of the parsing algorithm, macros in the
argument of \verb|\Shortstack| and \verb|\Longstack| may need to be
\verb|\protect|'ed.\mdseries

The alignment may be specified as an optional argument, with other
parameters taken by their defaults.  The stacklength is taken as
\vb|\stackgap|, which will depend on the value of \vb|\stacktype|.

To give an example of the braced syntax described above,
the stack\\
\vb|\Shortstack[r]{a {b c} {\P} $\beta^2$ ANCHOR}|
will produce
\Shortstack[r]{a {b c} {\P} $\beta^2$ ANCHOR}.

\subsubsection{\cmd{Shortunderstack} and \cmd{Longunderstack}}

The \vb|\Shortunderstack| and \vb|\Longunderstack| commands are the
understacking equivalents of \vb|\Shortstack| and \vb|\Longstack|.

\itshape
\vb|\Shortunderstack[|alignment%
  \vb|]{|anchor item %
  \vb|{|it em%
  \vb|} {\|item%
  \vb|} $|item%
  \vb|$| ...%
  \vb|}|\\
\vb|\Longunderstack[|alignment%
  \vb|]{|anchor item %
  \vb|{|it em%
  \vb|} {\|item%
  \vb|} $|item%
  \vb|$| ...%
  \vb|}|
\upshape

The caveats to the specification of the space-separated list of items is
the same as that mentioned above for \vb|\Shortstack| and
\vb|\Longstack|.

Note that the items are still specified from the top downward.
In the case of understacks, however, that means that the anchor is the
first item specified, while the last item in the list is farthest below
the baseline.

\subsubsection{Top and bottom lapping macros\label{s:lapdef}}

\tclap{Top}and \bclap{bottom}~lapping is achievable through the creation of various
long stacks.  The syntax is the same for all six of the macros provided.
The six names differentiate whether the lap is to the top (t) or the
bottom (b) of the calling point, and whether it should appear to the
left (l), centered (c), or to the right (r) of the calling location.
The long-stacklength may be provided as an optional argument.

\itshape
\vb|\tllap[|stacklength\vb|]{|item\vb|}|\\
\vb|\tclap[|stacklength\vb|]{|item\vb|}|\\
\vb|\trlap[|stacklength\vb|]{|item\vb|}|\\
\vb|\bllap[|stacklength\vb|]{|item\vb|}|\\
\vb|\bclap[|stacklength\vb|]{|item\vb|}|\\
\vb|\brlap[|stacklength\vb|]{|item\vb|}|
\upshape

See \S\ref{s:lap} for more information and examples of use for
these lapping commands.  If trying to remember the names of all these
lapping commands is too tedious for you, two functionally identical
macros have been introduced:

\itshape
\vb|\toplap[|stacklength\vb|]{|lap H-direction\vb|}{|item\vb|}|\\
\vb|\bottomlap[|stacklength\vb|]{|lap H-direction\vb|}{|item\vb|}|
\upshape

The names are simpler to remember, but they require, as their first
mandatory argument, the horizontal direction of lapping (l, c, or r),
while the material to be lapped is now in the second mandatory argument.

\subsubsection{\cmd{stackanchor}}

The \vb|\stackanchor| macro is one way to create a stack where the
baseline is split between two items in the stack.  The syntax is

\itshape
\vb|\stackanchor[|stackgap%
  \vb|]{|top item%
  \vb|}{|bottom item%
  \vb|}|
\upshape

The stacking gap may be provided as an optional argument.  All other
parameters taken are the defaults.  There are subtle differences in the
way a short stack anchor versus a long stack anchor is split.
One should consult \S\ref{s:sa} for a description of how the
stack is constructed.

If a short stack is being created with a split anchor, the
\vb|\usestackstrut| parameter will determine whether the split occurs
at the mid-height of the strutbox (``T'') or whether it will occur about
the baseline (``F'').

If a long stack is to be created with a split anchor, it is best to
formulate and \vb|\savestack| both the upper portion (with a stack)
and the lower portion (with an understack), and then \vb|\stackanchor|
the two parts together.

\subsubsection{\cmd{abovebaseline} and \cmd{belowbaseline}}

The macros \vb|\abovebaseline| and \vb|\belowbaseline| also creates the
means to shift an item's baseline.  The syntax is

\itshape
\vb|\abovebaseline[|stackgap\vb|]{|item\vb|}|\\
\vb|\belowbaseline[|stackgap\vb|]{|item\vb|}|
\upshape

where the stackgap defines the stackgap distance.  In a long stack, it
will define the upward (for \vb|\abovebaseline|) or downward shift
(for \vb|\belowbaseline|) of the baseline of the item.  In a short
stack, it will define the upward/downward vertical gap between the
original baseline and the bottom/top of the shifted item.

For long stacks, a negative stackshift for \vb|\belowbaseline| will
produce the same result as the corresponding positive stackshift for
\vb|\abovebaseline|.  But this will not be the case for short stacks.
One should consult \S\ref{s:bbl} for more details.

This command can also be employed to redefine the baseline of graphical
objects, which can provide a useful technique to achieve horizontal
alignment with other objects.  Negative stack gaps are valid (see
\S\ref{s:bbl} for examples).

\subsubsection{{\cmd{topinset}} and \cmd{bottominset}\label{s:iis}}

The macros \vb|\topinset| and \vb|\bottominset| are for insetting
smaller items (\textit{e.g.}, images) inside of a larger background
items (\textit{e.g.}, images).  The syntax is

\itshape
\vb|\topinset{|inset item%
  \vb|}{|background item%
  \vb|}{|V-offset%
  \vb|}{|H-offset\vb|}|\\
\vb|\bottominset{|inset item%
  \vb|}{|background item%
  \vb|}{|V-offset%
  \vb|}{|H-offset\vb|}|
\upshape

In addition to providing the inset and background items as the first two
arguments, the inset may be vertically and horizontally offset though
the use of the last two arguments.  The vertical offset is relative to
the top of the \vb|\topinset| background and relative to the bottom of
the \vb|\bottominset| background.  The horizontal offset is relative
to the left edge of the background for left stackalignment and relative
to the right edge of the background for right stackalignment.
Horizontal offset is meaningless for center stackalignment.

While these commands were designed with inlaid images in mind (see
\S\ref{s:ii}), there is nothing that prevents their use to inlay
character glyphs upon each other, as in 
\topinset{*}{O}{0.2ex}{0.0ex}, accomplished with
\vb|\topinset{*}{O}{0.2ex}{0.0ex}|.


\subsubsection{\cmd{savestack}}

The macro \vb|\savestack| provides a means to save an intermediate
result (in a box that can be recalled with the specified macro) without
printing it.  It's syntax is

\itshape
\vb|\savestack{|macro token\vb|}{|stacking operation\vb|}|
\upshape

The macro token is a backslashed name that you can later use to recall
the boxed intermediate result.  The stacking operation is the
intermediate result you wish to save in a box without printing.  Reasons
why this might be a useful macro are described in \S\ref{s:svs}.

Note that while \vb|\savestack| is designed to save an intermediate
stacking operation in a box, the reality is that you can use this macro
to save any sequence of boxable output, even if it is not a stacking
operation.  So, for example, \vb|\savestack{\mymacro}{\fbox{A}}| can
later be recalled with an invocation of \vb|\mymacro|, to yield
\fboxsep=1pt\savestack{\mymacro}{\fbox{A}}\mymacro.\fboxsep=0pt

\section{Making a Stack in Stages}

There are times where one needs to make a stack in several consecutive
steps.  In order to do so, there are several ways, detailed below.  

\subsection{Supressing Output\label{s:qs}}

One can define \vb|\quietstack| as \vb|T| to supress output.  Then, the
intermediate stack can be passed as an argument to the next stacking
operation with a \vb|\usebox{\stackedbox}|.  That same \vb|\usebox|
may be used to output the final stack, as long as \vb|\quietstack|
remains defined as ``T''.  Otherwise, \vb|\quietstack| must again be
defined ``F'' (false) to re-enable automatic output.

\subsection{Saving a Stack without Printing It\label{s:svs}}

Perhaps a quicker and better way is to use the package's
\vb|\savestack| macro, of the form
\itshape\vb|\savestack{|macro token\vb|}{|stacking operation\vb|}|
\upshape.  This will perform the stacking operation and place it into
the supplied token (without printing it), so that ths intermediate stack
can be passed to the subsequent stacking operation by executing the
token macro.

For example,
\begin{verbatim}
\savestack{\pdq}{\Longstack[r]{6 5 4 {3 3}}}%
\Longstack[l]{{\pdq} 2 1 0}%
\end{verbatim}

would first place ``\Longstack[r]{6 5 4 {3 3}}'' into \vb|\pdq|, without
printing it, in a right-aligned fashion, with the ``3 3'' on the
baseline.  Then, the second \vb|\Longstack| would place the first stack
atop of the ``2'' in a left-aligned fashion.  The resulting stack would
look as follows, with the ``0'' on the final baseline.

\savestack{\pdq}{\Longstack[r]{6 5 4 {3 3}}}%
\Longstack[l]{{\pdq} 2 1 0}
\rl\rl\blmark%

\section{Choosing the Anchor Element}

All stacking done with the stackengine has a designated anchor element.
The baseline of the anchor does not change.  Instead, the other items
are placed relative to the anchor.
By adding items at first above and then below the anchor, any
arbitrary stack can be built around the anchor.

\def\stackalignment{r}
\setstackgap{S}{2pt}\setstackgap{L}{12pt}%
Here is a Longstack/understack example:
\savestack{\pdq}{\Longstack{3 2 1 0}}%
\Longunderstack[r]{{\pdq} -1 -2 -3 -4 -5}
that was achieved as follows:

\begin{verbatim}
\savestack{\pdq}{\Longstack{3 2 1 0}}%
\Longunderstack[r]{{\pdq} -1 -2 -3 -4 -5}
\end{verbatim}

In the first stack, ``0'' is the anchor of \vb|\pdq|.  In the second
stack, \vb|\pdq| is the anchor (which means that ``0'' remains the
anchor of the composite stack).

\section{Top and Bottom Lapping\label{s:lap}}
\def\stackalignment{c}
\def\stacktype{L}%
\setstackgap{L}{\baselineskip}
Top and bottom lapping can be accomplished with a long stack, using a null
item as the anchor, and \vb|\useachorwidth| set to \vb|T|.  This
technique is encoded in six \vb|\|\textit{xy}\vb|lap| commands,
where \textit{x} can be \vb|t| or \vb|b| (for ``top'' and
``bottom,'' respectively) and \textit{y} can be \vb|l|, \vb|c|, or
\vb|r| (for ``left,'' ``center,'' and ``right,'' respectively).  Note
that this \textit{y} is not the same as the \vb|\stackalignment|, but
rather refers to the direction where the lapped item is placed relative
to the lap invocation.

For illustration only, laps will be shown at a \textit{visible} lapmark
(given by \lapmark~), defining the point of invocation.  In these
examples, I lap a \vb|\parbox| above or below the selected location.

\begin{myverbbox}{\bll}\bllap\end{myverbbox}
\begin{myverbbox}{\brl}\brlap\end{myverbbox}
\begin{myverbbox}{\tll}\tllap\end{myverbbox}
\begin{myverbbox}{\trl}\trlap\end{myverbbox}
\begin{myverbbox}{\bcl}\bclap\end{myverbbox}
\begin{myverbbox}{\tcl}\tclap\end{myverbbox}
For example here\lapmark%
\bllap{\parbox[t]{.7in}{this is a bottom-left lap \bll}}
or el\lapmark%
\brlap{\parbox[t]{.8in}{this is a bottom-right lap \brl}}%
se here, or else I can put it here\lapmark%
\tllap{\parbox[b]{.7in}{this is a top-left lap \tll}}
or here\lapmark%
\trlap{\parbox[b]{.7in}{this is a top-right lap \trl}}%
.\

Of course, I can per\lapmark
\bclap{\fbox{\parbox[t]{1.1in}{this is a bottom-center lap \bcl}}}%
form center lapping, as we\lapmark%
\tclap{\fbox{\parbox[b]{1.1in}{this is a top-center lap \tcl}}}%
ll.
To see, for example, how the above was achieved, the last lap in the
prior sentence was achieved by invoking

\vb|\tclap{\fbox{\parbox[b]{1.1in}{this is a top-center lap \tcl}}}|

in the middle of the word ``well.''  (Note that \vb|\tcl| is a box
containing the verbatim text ``\tcl,'' created with the
\textsf{verbatimbox} package.)

Note that \vb|\toplap| and \vb|\bottomlap| have also been introduced
as macros that are functionally identical to these six lapping commands.
While requiring an extra argument, their names may be easier for you to
remember.  See section~\ref{s:lapdef}.

\section{Shifting the Anchor's Baseline} 

By default, the baseline of the anchor becomes the baseline of the
stack.  If one wanted the stack baseline to \textbf{not} conform to
the baseline of any of the individual stacked items, something needs
to change.  If one quantitatively knows the shift desired, a simple
\vb|\raisebox| could be used to vertically shift the anchor, after
(or possibly prior to) stacking.  There are also some other options
provided by the package.

\subsection{The \cmd{stackanchor} Macro for ``L'' and ``S'' Stack Types%
\label{s:sa}}

If one would like the anchor's baseline to be ``midway'' between two
vertically arrayed items, the \vb|\stackanchor| macro attempts to
provide that capability for both ``L'' and ``S'' stack types, though the
definitions of ``midway'' are different for each.  The macro
\vb|\stackanchor| works for two-item stacks in both ``L'' and ``S''
stack types, as shown below.

In the case on a long stack, what is satisfied is that the baseline of
the anchor is made equidistant from the baselines of the two respective
items comprising the stacked anchor.

\def\stacktype{L}%

\Large
\def\stackalignment{r}%
\setstackgap{L}{.8\baselineskip}%
\blmark%
\rl\rl
\stackanchor{\rl\rl\rl\rl top\rl}{\rl L-bottom\rl}%
\rl\rl%
\blmark
\normalsize

In the case of a short stack, the middle of the inter-item gap is
vertically located at the center of the font's \vb|\strutbox|, so that
the middle of the stackgap would be at the same vertical level as the
middle of parentheses, were they located on the original baseline.

\Large
\blmark\rl\rl%
\def\rls{\rule[.5\ht\strutbox-.5\dp\strutbox]{2ex}{.1pt}}%
\rls%
\def\stackalignment{l}%
\def\stacktype{S}\setstackgap{S}{1ex}%
\savestack{\pdq}{\stackanchor{\fbox{top}}{\fbox{S-bottom}}}%
\pdq%
\rls%
(Mid-strut)%
\rl\rl\blmark
\def\stackalignment{c}%
\normalsize%

If one does not want to have the short-stack gap split at the mid-strut
height, but rather at the baseline, the parameter
\vb|\def\usestackstrut{F}| may be set prior to the \vb|\stackanchor|
invocation.

\def\usestackstrut{F}%
\Large
\blmark\rl\rl%
\def\stackalignment{l}%
\def\stacktype{S}%
\savestack{\pdq}{\stackanchor{\fbox{top}}{\fbox{S-bottom}}}%
\pdq%
\rl\rl\blmark
\def\stackalignment{c}%
\normalsize%
\def\usestackstrut{T}%

The \vb|\usestackstrut| parameter will only affect short stacks
(\vb|\stacktype| ``S''), since long stacks do not use a strut as part
of the \vb|\stackanchor| definition.

For stackanchors with more than two rows, one should compose the top
portion with a stack and the bottom portion with an understack, and
then, finally, shift the anchor by applying \vb|\stackanchor|.

\Large
\setstackgap{S}{1ex}%
\savestack{\upperstack}{\Shortstack{{over text} {\fbox{top}}}}
\savestack{\lowerstack}{\Shortstack{{\fbox{S-bottom}} {under text}}}
\blmark\rl\rl\rls%
\stackanchor{\upperstack}{\lowerstack}%
\rls(Mid-strut)
\normalsize

\subsection{\cmd{belowbaseline} for Moving the Anchor's
Baseline\label{s:bbl}}

The command \vb|\belowbaseline| is intended to be used to set an item,
such as a stack anchor, below the baseline (this discussion is equally
valid for the macro \vb|\abovebaseline|, but in the opposite sense).
The macro accomplishes this task by stacking the item below a null
object.  However, \vb|\useanchorwidth| is temporarily set to \vb|F| so
that the stacked object takes on the width of the under-placed object.

The command can be used with both stacktypes.  With \vb|\stacktype|
``S'', the optional argument will denote the stackgap below the baseline
(default \vb|\Sstackgap|),

\Large
\setstackgap{S}{6pt}%
\def\stacktype{S}%
Short stacktype\rl\rl\belowbaseline[0pt]{\fbox{0pt below baseline}}%
\rl\belowbaseline{\fbox{6pt}}\rl\belowbaseline[-6pt]{\fbox{-6pt}}\rl\rl
\normalsize

When used in with a \vb|\stacktpe| ``L'', the optional length denotes
the distance to the baseline of the understacked object (default
\vb|\Lstackgap|).

\Large
\setstackgap{L}{18pt}%
\def\stacktype{L}%
Long stacktype\rl\rl\belowbaseline[0pt]{\fbox{0pt below baseline}}%
\rl\belowbaseline{\fbox{18pt}}\rl\belowbaseline[-19pt]{\fbox{-18pt}}\rl
\normalsize

As the above images show, there is nothing to prevent the use of
negative numbers being used to raise the the object above the baseline.
But care must be taken, since a \vb|\belowbaseline| with a negative
shift will not necessarily equal the \vb|\abovebaseline| with the
corresponding positive shift (that equality only holds for long stacks).
To better appreciate the meaning of negative baseline shifts, we
compare, below, negative shifts for \vb|\belowbaseline| to
\vb|\abovebaseline| with the corresponding positive argument.

\Large
\def\stacktype{S}%
Short stacktype\rl\rl\belowbaseline[-6pt]{\fbox{-6pt below}}%
\rl\abovebaseline[6pt]{\fbox{6pt above}}\rl\rl\blmark%
\normalsize

\Large
\def\stacktype{L}%
Long stacktype\rl\rl\belowbaseline[-6pt]{\fbox{-6pt below}}%
\rl\abovebaseline[6pt]{\fbox{6pt above}}\rl\rl\blmark%
\normalsize

The \vb|\belowbaseline| command is also useful for forcing objects,
such as images, to be top-aligned.  This can be a useful feature when
trying to achieve a desired horizontal alignment of disparate elements in
tabular columns.

\vb|\def\stacktype{S}\belowbaseline[0pt]{\imgi}|\\
\vb|\belowbaseline[0pt -\heightof{\strutbox}]{\imgi}|:

\def\stacktype{S}
\def\imgi{\includegraphics[width=0.87in]{example-image}}
\rl\blmark\rl\rl\belowbaseline[0pt]{\imgi}\rl\rl
\belowbaseline[0pt -\heightof{\strutbox}]{\imgi}\rl\rl%
\fbox{\parbox[t]{1.8cm}{\raggedright A parbox with [t] alignment}}%
\rl\rl\blmark\rl

\section{Negative Stack Gap}
\def\stacktype{S}
\setstackgap{S}{-1.2pt}
\setlength{\dotscale}{1.ex}
A negative gap can be used to overlap things.  For example, \newdot plus
``i'' can make, when the stack gap is suitably negative, the following:

~\hfill\scalebox{3}{\stackon{i}{\newdot}}\hfill~

Note that the use of a negative stack gap for a two-item stack is
actually very similar to the inset commands described in
\S\ref{s:iis} and \S\ref{s:ii}.  The issue of negative stackgaps is also
discussed in section~\ref{s:bbl}.

\section{The {\cmd{useanchorwidth}} Option\label{s:uaw}}
\setstackgap{S}{-1.2pt}
\setlength{\dotscale}{1.ex}

Because\newdot has width larger than the dot glyph itself (we box its
extent here: \fbox{\newdot}), stacking it could otherwise be a problem.
For example, th\stackon{i}{\newdot}s uses the whole stackwidth to set
the dotted-i in its place. 
\def\useanchorwidth{T} 
On the other hand, when \vb|\useanchorwidth| is defined as \vb|T|,
``th\stackon{i}{\newdot}s'' uses only the anchor width to set the stack
(where the ``i'' is the anchor).  

Below, we show an \vb|\fbox| around the dotted i, clearly
demonstrating that the dot does not influence the width of the
stack when \vb|\useanchorwidth| is defined as ``T''.

\fboxrule=0.2pt
\hfill 
\scalebox{3}{th\fbox{\stackon{i}{\newdot}}s}%
\hfill~
\normalsize
\def\useanchorwidth{F} 
\fboxrule=0.6pt

\section{Image Insets\label{s:ii}}

The commands \vb|\topinset| and \vb|\bottominset| allow images to be
stacked atop one another, to produce the effect of an inset image.  In
addition to specifying the two images, the effect can be tailored by
specifying the vertical and horizontal offset of the inset image.

\def\imgi{\includegraphics[width=0.87in]{example-image}}
\def\imgii{\includegraphics[width=0.3in]{example-image}}
\def\stackalignment{r}
\savestack{\imga}{\topinset{\imgii}{\imgi}{2pt}{3pt}}
\def\stackalignment{l}
\savestack{\imgb}{\bottominset{\imgii}{\imgi}{2pt}{3pt}}
\imga~~~~\imgb
\def\stackalignment{c}

Note that the horizontal offset only works when \vb|\stackalignment|
is set to \vb|l| or \vb|r|.

The last figure was obtained with
\vb|\bottominset{\imgii}{\imgi}{2pt}{3pt}|,
showing that \vb|\imgii| was offset 2pt from the bottom and 3pt from
the left edge of \vb|\imgi|.

\section{Stacking for Subfiguring and Baseline Manipulation}

The stacking commands provide a convenient way to underset a subfigure
notation under the corresponding image.  Furthermore, because of the
flexibility of the stacking commands, the baselines of the subfigures
can be manipulated in many ways, which may come in handy depending on
how you are choosing to lay out your subfigures.

Examples of this are shown in figure~\ref{fg:subs}.
%
\setstackgap{S}{3pt}\def\stacktype{S}%
\begin{myverbbox}{\figa}\stackon{(a)}{\imga}\end{myverbbox}%
\begin{myverbbox}{\figb}\stackunder{\imgb}{(b)}\end{myverbbox}%
\begin{myverbbox}[\small]{\figc}
\Shortstack{{\protect\imgi} (c1) {} {\protect\imgi} (c2)}
\end{myverbbox}%
\begin{myverbbox}%
{\figd}\belowbaseline[0pt]{\stackunder{\imgi}{(d)}}\end{myverbbox}%
\def\CaptionJustification{\raggedright}%
\bxfigure[ht]
{Image stacking with stacktype ``S'', stack gap set to 3pt and using: 
(a)~\figa, (b)~\figb, (c)~\figc, and (d)~\figd\label{fg:subs}}
{\blmark\rl\rl%
\stackon{(a)}{\imga}~~
\stackunder{\imgb}{(b)}~~
\Shortstack{{\protect\imgi} (c1) {} {\protect\imgi} (c2)}~~
\belowbaseline[0pt]{\stackunder{\imgi}{(d)}}
}%
Note from the definition used for figure~\ref{fg:subs}(c) that when a
\vb|\savestack| has been used to place a graphic into a token
(\textit{e.g.}, \vb|\imgi|) that it must be protected when used inside
a space-separated argument, such as \vb|\Shortstack|,
\vb|\Longstack|, and the corresponding understacks.

\section{Nested Stacking Commands}

The macros \vb|\Shortstack|, \vb|\Longstack|, and the corresponding
understack macros are set up to conveniently stack multiple objects
using a space separated argument list.  Because of parsing constraints
on the space-separated list, however (see \S\ref{s:mm}), there may be
times that you would prefer building stacks by way of nesting the more
primative stacking macros.

Nesting can be accomplished, but some care must be taken, in the case of
long stacks.  But first, let us see the ways in which nesting may be
applied for short stacks:\\

\def\stacktype{S}\setstackgap{S}{3pt}
\vb|\stackunder{1}{\stackunder{2}{\stackunder{3}{\stackunder{4}{5}}}}|\\
\vb|\stackunder{\stackunder{\stackunder{\stackunder{1}{2}}{3}}{4}}{5}|\\
\vb|\stackon{1}{\stackon{2}{\stackon{3}{\stackon{4}{5}}}}|\\
\vb|\stackon{\stackon{\stackon{\stackon{1}{2}}{3}}{4}}{5}|

will produce the following: 
\stackunder{1}{\stackunder{2}{\stackunder{3}{\stackunder{4}{5}}}}
\stackunder{\stackunder{\stackunder{\stackunder{1}{2}}{3}}{4}}{5}
\stackon{1}{\stackon{2}{\stackon{3}{\stackon{4}{5}}}}
\stackon{\stackon{\stackon{\stackon{1}{2}}{3}}{4}}{5} \blmark

In these cases, the nesting could be applied on either the first or the
second argument of the \vb|\stackunder| or \vb|\stackon| commands,
with the same end result.

In the case of long stacks however, employing the identical methodology
gives a different, at first unexpected, result:
\def\stacktype{L}\setstackgap{L}{\baselineskip}
\stackunder{1}{\stackunder{2}{\stackunder{3}{\stackunder{4}{5}}}}
\stackunder{\stackunder{\stackunder{\stackunder{1}{2}}{3}}{4}}{5}
\stackon{1}{\stackon{2}{\stackon{3}{\stackon{4}{5}}}}
\stackon{\stackon{\stackon{\stackon{1}{2}}{3}}{4}}{5} \blmark

In this case, nesting the second argument works as hoped, but nesting
the first argument does not.  The reason for this ``failure'' stems
not from a failure of logic, but an enforcement of it.  It stems from the
very definition of a long stack, in which the baseline of the second
argument is placed \vb|\LStackgap| below or above the baseline of the
first argument.  By nesting the first argument, all the second arguments
are placed \vb|\Lstackgap| from the unchanging stack baseline (thus
overlapping), and not relative to the current top or bottom of the
nested stack.

Therefore, to nest long stacks, only the second argument of the
stackengine may be nested.

\section{Math Mode Usage\label{s:mm}}
\def\useanchorwidth{F}
\setstackgap{S}{1pt}\def\stacktype{S} 

The \textsf{stackengine} package is not really intended for math mode,
since there are many packages that already cater directly to the need to
stack and align mathematical objects.  However, if there is a need to
use {\ste} there, because of its particular facility with
stacking gaps, there are several hints to remember.

%SAVE FOR FUTURE USE
\begin{verbbox}[]
\savestack{\a}{\(\sqrt{a + b}\)}
\savestack{\dash}{- - - - -}
\(y = \stackunder{\stackon{\dash}{\a}}{$b$} x\)
\end{verbbox}

\begin{enumerate}

\item Stacking commands from this package can be used in math mode, but will
set their arguments as text, not math.

\vb|\( y = \stackunder{a}{+} x\)|:\hfill
\( y = \stackunder{a}{+} x\)

\item To set an argument in math style, it must be set between math
delimiters.

\vb|\( y = \stackunder{\(a\)}{+} x\)|:\hfill
\( y = \stackunder{\(a\)}{+} x\)

\item Each space-separated item of the argument to \vb|\Shortstack|,
\vb|\Longstack|, and the corresponding understacks must each be enclosed
in their own set of dollar-sign math delimiters (Because of the way the
argument is parsed, the \vb|\(| and \vb|\)| delimiters can be used, but
only if \vb|\protect|'ed, in these space-separated argument lists).

\vb|\(y = \Shortstack{$a$ . $b$} x\)|:\hfill
\(y = \Shortstack{$a$ . $b$} x\)

\item As described in \S\ref{s:sls}, if the math argument has
spaces in a command which uses space-separated lists, the argument must
be enclosed in braces.

\vb|\(y = \Shortstack{{$a + b$} . $b$} x\)|:\hfill
\(y = \Shortstack{{$a + b$} . $b$} x\)

\item For more complex items, the \vb|\savestack| command can be used
to save an intermediate math expression (even if it isn't actually a
stack).

\theverbbox:\hfill
\savestack{\a}{\(\sqrt{a + b}\)}
\savestack{\dash}{- - - - -}
\addvbuffer[\the\baselineskip]{\(y = \stackunder{\stackon{\dash}{\a}}{$b$} x\)}

\item In math mode, the \vb|\stackanchor| command seems to preserve
the math axis better with an ``S'' \vb|\stacktype|, rather than type
``L''.

\end{enumerate}

\section{Backward Compatibility\label{s:bc}}

The author of this package profoundly apologizes for the fact that the
syntax of this package has changed between versions 1.0 and 2.0 of this
package.  

In version 1.0 of this package, stackgaps could be directly defined by
setting the \LaTeX{} lengths \verb|\Sstackgap| and \verb|\Lstackgap|.
The problem with this approach is that, under fontsize changes, these
stackgaps were not automatically updated to reflect the new fontsize.
As of V2.0, that deficiency was remedied.  The syntax that replaces
these length specifications is

\itshape
\vb|  \setstackgap{S}{|inter-item stackgap\verb|}|\\
\vb|  \setstackgap{L}{|inter-item baselineskip\verb|}|  .
\upshape

Thus, \verb|\Sstackgap| and \verb|\Lstackgap| are no longer lengths (but
instead \verb|\def|s), and cannot be set via the \verb|\Sstackgap=...|
or \verb|\setlength{\Sstackgap}{...}| syntax.  It is these settings
which will need to be revised to modernize older code.

While not encouraged, the V1.0 syntax may be recovered via

\verb|  \usepackage[oldsyntax]{stackengine}|

If you retain the ``oldsyntax'' setting, you must remember that
\textsf{stackengine} will honor your specified gap sizes
(\vb|\Sstackgap| and \vb|\Lstackgap|) at the time of their
\textbf{definition}, rather than at the time of their
\textbf{invocation}.  Thus, if \vb|\Sstackgap| is specified as 0.7ex
when the text is \vb|\normalsize|, the gap length is set in a
\vb|\normalsize| font, even if the fontsize is later changed.  To
overcome this behavior, the stackgap must be redefined at the new
fontsize, or better still, \verb|[oldsyntax]| usage needs to be
relegated.

\section{Acknowledgements}

I would like to thank Prof. Enrico Gregorio at tex.stackexchange for
providing three lines of code to strip a leading backslash from an
argument:\\
\verb|http://tex.stackexchange.com/questions/42318/|\\
\verb|removing-a-backslash-from-a-character-sequence|

Furthermore, Prof. Gregorio was of great assistance in making the
transition from the deficient V1.0 syntax as painless as possible:\\
\verb|http://tex.stackexchange.com/questions/123443/|\\
\verb|defining-a-length-that-scales-with-fontsize-changes/123470#123470|

\section{Code Listing}

\verbfilenobox[\footnotesize]{stackengine.sty}

\end{document}