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<div class="moz-cite-prefix">On 16/04/2023 17:37, Jonathan Kew
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:87e0b1f4-bdfb-c1de-8e1e-1a8eefaf0127@gmail.com">First
note: I see the same result with plain TeX. So not a XeTeX issue.
<br>
</blockquote>
Agreed, but as I use only XeTeX this seemed the right place to ask.
I did test with PdfTeX (not having plain TeX in my TeXworks armoury)
and PdfTeX did much the same but put a real <tab> in the
transcript as opposed to ^^I.<br>
<blockquote type="cite"
cite="mid:87e0b1f4-bdfb-c1de-8e1e-1a8eefaf0127@gmail.com">Anyway,
this is expected behavior. The ^^I isn't part of the offending
control sequence; it's just the preceding context on the line,
which is what normally appears in a TeX error message.
<br>
</blockquote>
OK, so I should have realised that in the absence of a leading "\",
^^I~ could not possibly be a control sequence and therefore the "~"
had to be an active character. That fact had passed me by ...<br>
<blockquote type="cite"
cite="mid:87e0b1f4-bdfb-c1de-8e1e-1a8eefaf0127@gmail.com">Ignored
characters are not "removed from the input" (despite anything
Eijkhout says); they're still present, just ignored. <br>
</blockquote>
<p>Having consulted Eijkhout first, I did then search the TeXbook to
see if I could find a definitive statement concerning the
treatment of ignored characters but failed to do so — perhaps I
should search the PDF version rather than the printed ...</p>
<p>-- <br>
<i>Philip Taylor</i><br>
</p>
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