[XeTeX] \ifincsname: unexpected behaviour after nested \csname...\endcsname

Will Robertson wspr81 at gmail.com
Thu Jul 22 06:20:27 CEST 2010

On 2010-07-22 09:12:14 +0930, Grzegorz Murzynowski 
<natror at o2.pl> said:

> I noted quite unexpectedly that nesting \csname…\endcsname, results in 
> turning |\ifincsname| false: the example above typesets
> 	\before nested csname: In csname \ after nested csname: Not in csname
> Is it a bug or a feature? (I use nested csnames sometimes).

The same behaviour occurs in pdfTeX, so from that respect at least it's 
consistent. But it definitely looks like a bug to me.

Perhaps a clarifying example:

\def\a{\ifincsname T \else F \fi}

#1 and #2 and "true" but #3 is "false". Clearly the \endcsname has 
reset the "am i in a csname" switch rather than popped it back to its 
previous value.

I think it would be worth sending this to the pdfTeX mailing list as well.


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