[XeTeX] XeTeX does not define the \XeTeX macro.

[Martin Schröder]

2011/12/21 Philip TAYLOR <P.Taylor at rhul.ac.uk>:
> The following code fragment, from plain XeTeX source,
> results in an "undefined control sequence : \XeTeX"
> message.  Where is \XeTeX canonically defined, please ?

Nowhere.

Even tugboat doesn't do it in plain:
%  the Xe\TeX logo requires Eplain, which is not assumed here, so
%  the definition is omitted.

Best
   Martin

PS: The LuaTeX logo is also not available automatically in luatex.