# [OS X TeX] New TeX i-Package in the *EXPERIMENTAL* i-Directory

Gary L. Gray gray at engr.psu.edu
Sat Sep 10 20:13:27 CEST 2005

This is a reply from Karl Berry to Bruno's recent post ...

>> - \ifx\pdfoutput\undefined will no longer work to detect whether
>>

This is nothing new.  The change was made in teTeX 3.0, thus I expect
has been in gwTeX for some time.

Thomas Esser went to a good deal of trouble to get packages changed.
The mere fact that \ifx\pdfoutput\undefined or \@ifundefined{pdfoutput}
is used does not mean that anything is broken.  In fact, the standard
way to detect it, as used in (for example) ifpdf.sty, is to check first
if \pdfoutput is defined, and if so, then check if \pdfoutput is > 0.

As far as I know, the only real impact is on *user* documents which
might use \ifx\pdfoutput\undefined or the equivalent to conditionally
load packages (or whatever).  They will now break.  They have to be
changed to use ifpdf.sty or equivalent logic.

Whether XeTeX packages need adaptation is something I don't know if
Thomas checked.  I rather doubt he checked anything not on CTAN.

But, to repeat, the only thing that's changing here is TL.  teTeX has
had this change since 3.0.

karl

P.S. I personally did not favor making this change at this time :).

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