[NTG-context] math symbols missing?

I just tried recompiling an old document with the latest minimals (mkiv) and found that some of my old math commands don't seem to work: \ulcorner \urcorner \cap Probably there are others, too. (Also, \showmathcharacters seems to be undefined.) Any idea what might be going on? Thanks, Jesse -- Jesse Alama (alama@stanford.edu)