fontifying of user defined variables

[dieter]

Hi

I'd like to highlight user specified variables in a major mode for a simple 
macro language (Ansys parametric design language or APDL). 

All number variables are specified with the following assignment:

VARIABEL=VALUE

I'd like to fontify in a certain face any variable VARIABLE which was defined 
in such a way and appears after the definition anywhere in the code.

Could you please outline the method or point to a lisp file where such a 
"dynamic" highlighting is accomplished.

--
  Dieter