Alan BRASLAU
18. August 2015 20:01
On Tue, 18 Aug 2015 19:42:20 +0200

I did not realize that \startchemical took the name of an instance as
argument - I have only used it with key=value, i.e.:
\startchemical[...=...]

I suppose that it uses some "standard" mechanisms.
There are helper commands for the default \define and \setup macros
but the allowed arguments for \start... depend only on the way how
you write it.
\definechemical[benzene] is different. It gets used as:

\startchemical
\chemical[benzene,...]
\stopchemical


Perhaps there is some inconsistency with respect to ConTeXt syntax here.
There are other commands which redefine the generated \define-command
but normally it is saved before the redefintion and the problem here is that
you can’t pass a instance because it can’t be created.

Wolfgang