[XeTeX] ifcat changed?

Philip Taylor P.Taylor at Rhul.Ac.Uk
Sun Apr 16 12:19:01 CEST 2017

Zdenek Wagner wrote:
> Not all control sequences but primitives.

Again, I would respectfully suggest that Knuth's own words are the best guidance here :

> *\**if *<token1> <token2>
> TeX will expand macros  following *\if* until two unexpandable tokens are found.  If either token is a control sequence, TeX considers it to have character code 256 and category code 16, unless the current equivalent of that control sequence has been *\let* equal to a non-active character token ...
> *\**ifcat *<token1> <token2>
> This is just like *\if*, but it tests the category code, not the character code ...

Philip Taylor

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