3.4.21 –ext_names=e

Create external names with or without trailing underscores.

e must be either plain, underscores, or fsecond-underscore The default is underscores.

–ext_names=plain: Do not add trailing underscore.

–ext_names=underscores: Add trailing underscore.

–ext_names=fsecond-underscore: Append two underscores to external names that contain an underscore, and a single underscore to those that do not.

An external name is a name of a subroutine, function, block data subprogram, or labeled common. This option affects both the name of the routine’s entry point and the name used in calls to it. Use this flag to allow Fortran routines to call (and be called by) other programming language routines.

fsecond-underscore is provided for compatibility with gfortran.