Trying to do some date and time processing myself, I ran into problems caused by ConTeXt makeing it incompatibel with the original plain TeX itself!
In the TeX-book, Appendix B one finds
<citation>
(Some parameters are set by TeX itself as it runs, so it is inappropriate to initialize them: \time, \day, \month, and year are established at the beginning of a job; ..
</citation>
Now the results in ConTeXT with a minimal example, put into the log for easier copying into the mail:
\starttext
\writestatus{}{\meaning\date -> \date}
\writestatus{}{\meaning\day -> \the\day}
\writestatus{}{\meaning\month -> \month WHY NOT monthname?}
\writestatus{}{\meaning\year -> \the\year}
\writestatus{}{\meaning\time -> \the\time}
\stoptext
Result:
> \protected macro:->\dodoubleempty \syst_converters_date -> \date
> \day-> 20
> macro:#1->\ctxcommand {monthname(#1)}-> \labeltext {unknown}HY NOT monthname?
> \year-> 2013
> \time-> 989
Plain TeX here gives:
\message{\meaning\day -> \the\day}
\message{\meaning\month -> \the\month}
\message{\meaning\year -> \the\year}
\message{\meaning\time -> \the\time}
\end
Result:
(./plaindates.tex \day-> 20 \month-> 3 \year-> 2013 \time-> 991 )
I strongly ask that ConTeXt abstains from changing the definition of \month and reverts to the exact result as given by plain TeX, i.e. a number in the range [1-12]. Because the change in ConTeXt makes it impossible to do calculations on the month.
Furthermore I encountered problems with defining expanded macros for currentdate and currenttime. This seems impossible to accomplish, at least in a simple manner. See the results from these to examples:
\edef\thedate{\currentdate}\writestatus{}{\meaning\thedate -> \thedate}
\edef\thetime{\currenttime}\writestatus{}{\meaning\thetime -> \thetime}
giving:
> macro:->\currentdate -> \currentdate
> macro:->\currenttime -> \currenttime
This is most unhappy, because one really should be able to put the expansions of these macros somewhere.
I hope the next beta will have solutions for these problems.