On 21/02/2011 12:07, Bruno Le Floch wrote:
>> I suspect condition (2) is  killer. While assuming "{" is catcode 1 is
>> fine for LaTeX-like input, what happens if you're using LaTeX3 with some
>> other input syntax (for example XML)?
> 
> Ok, the code can be changed so that the condition becomes
> 
> (2') There is only one character with catcode 1, and it is known when
> the package is loaded.

I'll give it some thought: as I'm most interested in a new kernel, 'load
time' is not 100% reliable. On the other hand, for internal processing
you can imagine that you might have to rescan material in any case, so
it might not be such an issue.
-- 
Joseph Wright