The CRTL Supplemental library provides functions typically found on Unix system, but are missing, incomplete, or incorrect on VMS. It is intended to make porting to VMS easier. It is also intended to provide prototype code that could later be incorporated into the CRTL. So this code is probably a bit rough. You should probably look at the code before using it to make sure it will serve your purposes.
When using GNV's cc driver, use of the library can be enabled by the -crtlsup switch or by defining the environment variable GNV_CRTL_SUP. The following is a list of functions currently included in the library:
Browse the CRTL Supplemental Library sources in the CVS Repository
If you have functions that you would like to contribute, send email to gnv-admin@lists.sourceforge.net.