[tex-hyphen] hyphenation different in xelatex?
P.Taylor at Rhul.Ac.Uk
Tue Sep 8 00:03:10 CEST 2015
Philip Taylor wrote:
> Reinhard Kotucha wrote:
>> And pdftex is 100% backwards compatible with DEK's TeX.
> Well, not really : compare the result of expanding (e.g.,)
> \expandafter \ifx \csname pdfximage\endcsname \relax UNDEFINED\else
> in the two engines ...
and of course, for exactly analogous reasons (\expandafter \ifx \csname
holdinginserts\endcsname \relax UNDEFINED\else DEFINED\fi), TeX 3 cannot
be 100% backwards-compatible with TeX 82. But there may be other
reasons as well, which it is too late for me to think of this evening.
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