FreeVMS Implemented Functions and Commands
There is some free implementation for each of the following
functions and commands. The quality may vary, it may or may not have
gotten much testing, &c.
rms$routines.h (part of starlet.h)
SYS$ (note that the version of SYS$NUMTIM here is better than the
one from the OpenVMS Freeware CD, VMS-UNDER-NT-BITS package).
SYS$FAOL (also here).
BASIC: See Basic/Plus to C++ translator from Kevin Handy
Jim Kingdon's Free-VMS page