g77 supports use of /* to start a trailing
comment.
In the GNU Fortran language, ! is used for this purpose.
/* is not in the GNU Fortran language
because the use of /* in a program might
suggest to some readers that a block, not trailing, comment is
started (and thus ended by */, not end of line),
since that is the meaning of /* in C.
Also, such readers might think they can use // to start
a trailing comment as an alternative to /*, but
// already denotes concatenation, and such a "comment"
might actually result in a program that compiles without
error (though it would likely behave incorrectly).