Hi Taco, I just finished reading the 'System_Macros'. I still don't get the meaning of '\??pb @lang@' in the following codes: \def\lang#1% {\def\biblanguage{#1}% \ifcsname \??pb @lang@#1\endcsname \expanded{\mainlanguage[\getvalue{\??pb @lang@#1}]}% \expanded{\language[\getvalue{\??pb @lang@#1}]}% \fi \ignorespaces} In \lang[zh], for example, '\??pb @lang@' will be expanded to \@@pblangen, will it? Is \??pb a command? Is '\??pb @lang@' a command? Why can there be a whitespace in '\??pb @lang@'? Sorry for some many questions. I'm so confused and don't know what to search in wiki, manuals, etc.. Best wishes, Wei-Wei Taco Hoekwater 写道:
Also generally helpful for a low-level understanding of context are these wiki pages: