Use: ftags [-m] [-_] file...

Purpose: create a tags file for Fortran files.

Restrictions: the Fortran word "function" or "subroutine"
must be space- or tab-delimited on the left, and appear on the
same line as the routine name.

Options:
-m	merge into existing tags file (default is to replace it).
-_	For all routines "xxx_", make a duplicate entry "xxx".