The two files Taco pointed to *appear* to be OK (though I'm too inexperienced to say with certainty). That leaves something esoteric or a tossed salad of old and new code. Since this is mainly a matter of learning and curiosity for me, I'll wait and see how things develop for a bit. Thanks for your help! mjg

...

I think either

/usr/local/texlive/texmf-local/tex/context/base/luat-env.tex

is not the one from the latest context distribution, or an extra luatools --generate command is needed.

You can check the \contextversion by looking at

/usr/local/texlive/texmf-local/tex/context/base/context.tex

around line 45, it should say

\edef\contextversion{2008.04.11 14:48}

There can be some more esoteric causes, but these are the two most likely ones.

in previou sversions the env was loaded runtime (this behaviour originated in the stepwise development of embedding bytecodes in the format, in the beginning all chunks were loaded at runtime); i managed to get rid of that; in addition to taco's suggestions ... so it could be that old code and new code is mixed.