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<p>Consider the following iniTeX program —</p>
<p>The "<font size="+1"><tt>&&</tt></font>" in line 5 causes
the remaining preamble elements (other than the <font size="+1"><tt>\cr</tt></font>)
to be repeated as many times as are required by the data that form
the body of the alignment (in this case, just "<font size="+1"><tt>&a&&b&\cr</tt></font>").
The <font size="+1"><tt>\tabskip = 0 pt </tt></font>at line 2
ensures that the first <font size="+1"><tt>\vrule </tt></font>aligns
with the left margin, and the <font size="+1"><tt>\tabskip = 0 pt
plus 1 fil </tt></font>of line 5 ensures that every cell is
nicely centered between its surrounding <font size="+1"><tt>\vrule</tt></font>
s. Unfortunately a problem occurs with the final column, where
once again we need [the effect of] <font size="+1"><tt>\tabskip =
0 pt </tt></font>to force the final<font size="+1"> </font><font
size="+1"><tt>\vrule</tt></font> to align with the right margin,
but because we are auto-repeating a part of the preamble, we have
no access to the preamble pattern which will be used for the final
column only. Inserting <font size="+1"><tt>\tabskip = 0 pt </tt></font>into
the body of the alignment at the appropriate point has no effect —
<font size="+1"><tt>\tabskip</tt></font> s are honoured only in
the preamble. Can anyone suggest how the final <font size="+1"><tt>\vrule
</tt></font>can be forced to align with the right margin, and
therefore with the right extremes of the <font size="+1"><tt>\hrule</tt></font>
s above and below ? A "hacky" solution would be to adjust the
width of the <font size="+1"><tt>\hrule</tt></font> s on an <i>ad
hoc</i> basis (e.g., <tt><font size="+1">\everycr = {\noalign
{\hrule width 0,805 \hsize}}</font></tt>), but this is ugly
and I would seek to avoid it if possible ...<br>
</p>
<ol>
<li><font size="+1"><tt>\everycr = {\noalign {\hrule}}</tt></font></li>
<li><font size="+1"><tt>\tabskip = 0 pt<br>
</tt></font></li>
<li><font size="+1"><tt>\halign to \hsize</tt></font></li>
<li><font size="+1"><tt>\bgroup</tt></font></li>
<li><font size="+1"><tt> \tabskip = 0 pt plus 1 fil #\vrule
height 3 ex depth 1 ex && \hfil #\hfil & #\vrule
\cr</tt></font></li>
<li><font size="+1"><tt><tt><tt> &a&&b&\cr</tt></tt></tt></font></li>
<li><font size="+1"><tt>\egroup</tt></font></li>
<li><font size="+1"><tt>\end</tt></font></li>
</ol>
<p><font size="+1">--<i><br>
Philip Taylor</i></font></p>
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