C-Fortran cocktail ('6000)

[Applied Magnetics]

This was partly a case of RTFM on my part.  I eventually found multiple
discussions of the interlanguage conventions in the *user's guides* of
C, Fortran and Pascal.  I had looked only in the reference manuals.
Things *not* mentioned are 1) common blocks;  2) interference between C
and Fortran I/O.   I'll try the keyword searches suggested by Russ
Heise.

Looking at object files with nm(1), I had figured out how to access
labeled Fortran commons from C.  The blank common generates a symbol
`#BLNK_COM', which is inaccessible from C.  I can't use a labeled
common because many modules don't know its size at compile time.
Instead, I changed the Fortran to pass an extra pointer when it calls C.

 --P. Asselin