/sys$common/syshlp/helplib.hlb FORTRAN, /BLAS, MAPPED  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Controls whether the Basic BLAS routines can be mapped to the
  appropriate OpenVMS Math Library or Compaq Extended Math Library
  routine, if the reference is not inlined or NOINLINE is in effect.

  If both NOINLINE and NOMAPPED are specified, Compaq Fortran 77 does not
  recognize BLAS routines as intrinsics.  If INLINE and NOMAPPED are
  specified, references that are not expanded inline cause the
  unmapped external routine name to be called.  For the Extended BLAS
  routines, the unmapped external routine name is always used if the
  reference is not expanded inline.