there are a few problems with the keywords for \date in MkIV.
\starttext
\starttabulate[|l|l|l|]
\NC keyword \NC MkII \NC MKIV \NC\NR
\NC day \NC 4 \NC \currentdate[day] \NC\NR
\NC day+ \NC 4 \NC \currentdate[day+] \NC\NR
\NC month \NC April \NC \currentdate[month] \NC\NR
\NC year \NC 2011 \NC \currentdate[year] \NC\NR
\NC d \NC 4 \NC \currentdate[d] \NC\NR
\NC d+ \NC 4 \NC \currentdate[d+] \NC\NR
\NC m \NC April \NC \currentdate[m] \NC\NR
\NC j \NC 2011 \NC \currentdate[j] \NC\NR
\NC y \NC 2011 \NC \currentdate[y] \NC\NR
\NC w \NC Monday \NC \currentdate[w] \NC\NR
\NC dd \NC 04 \NC \currentdate[dd] \NC\NR
\NC dd+ \NC 4 \NC \currentdate[dd+] \NC\NR
\NC mm \NC 04 \NC \currentdate[mm] \NC\NR
\NC jj \NC 11 \NC \currentdate[jj] \NC\NR
\NC yy \NC 11 \NC \currentdate[yy] \NC\NR
\NC weekday \NC Monday \NC \currentdate[weekday] \NC\NR
\NC referral \NC 20110404 \NC \currentdate[referral] \NC\NR
\stoptabulate
\stoptext