I'm looking for a tool to producing a cross-reference of where, in a set of
Ada units, objects declared in package specifications or bodies (aka
variables) are referenced (assigned or read).

Does anyone know where such a tool is available?  Alternative the location
of a similar tool that I could modify to this purpose.

Thanks, Rush Kester
P.S.  I know that global variables are "poor style."  I didn't write the
code, I'm just trying to understand it!