READONLY Keyword

Support for READONLY, in OPEN statements, requires libg2c support, to make sure that CLOSE(...,STATUS='DELETE') does not delete a file opened on a unit with the READONLY keyword, and perhaps to trigger a fatal diagnostic if a WRITE or PRINT to such a unit is attempted.

Note: It is not sufficient for g77 and libg2c (its version of libf2c) to assume that READONLY does not need some kind of explicit support at run time, due to UNIX systems not (generally) needing it. g77 is not just a UNIX-based compiler!

Further, mounting of non-UNIX filesystems on UNIX systems (such as via NFS) might require proper READONLY support.

(Similar issues might be involved with supporting the SHARED keyword.)