Hi Hans,

I made some testings with the new beta and noticed that there are a few maths characters or commands which are broken now.
Here is a minimal example:
%%%%%%% begin bug-lm.tex
\starttext
The commands \type{\imply} is not anymore defined.

\type{\iff}, \type{\Longrightarrow}, \type{\mapsto} and some other arrows do not appear.

\startformula
(\pi \notin {\Bbb Q} \Longrightarrow \pi^2 + \pi \not\in {\Bbb Q}) \iff \pi^2 \not\in {\Bbb Q}
\stopformula

\startformula
x \mapsto ax+b
\stopformula
\stoptext
%%%%%%% end bug-lm.tex

and the PDF output is attached.

Best regards: OK