[texhax] Some puzzling TeX

[Paul Isambert]

Le 22/02/2011 14:09, Uwe Lueck a écrit :
> "Donald Arseneau"<asnd at triumf.ca>  wrote 22.02.2011 13:24:54:
>> "Uwe Lueck"  writes:
>>>> On Sun, Feb 20, 2011 at 8:13 AM, Uwe Lueck  wrote:
>>>>> I am unable to get a catcode of \relax or \bgroup by \showthe\catcode.
>> This betrays a subtle misunderstanding.  There is no catcode of
>> \relax; only character tokens have category codes.
>>
>> However \catcode does not tell the category of a character token!
>> It only reports contents of the look-up table TeX uses to interpret
>> raw characters as they are input (or as they are re-scanned, in eTeX).
>> This has to be so since the argument for \catcode is a number, not
>> a token!
> Indeed just missed TeXbook p. 271: \catcode expects "8-bit number".
>
> I wonder at this point how this is with XeTeX and LuaTeX ...
> and cannot afford right now browsing their documentations ...

LuaTeX expects a number between 0 and 1,114,111 (the largest Unicode 
code point).
As for XeTeX, I suppose it depends on the encoding being used, but I 
haven't tried.

Best,
Paul