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

  If defined during compilation, this logical name specifies one or
  more default text libraries to be searched for library-based
  INCLUDE statements which do not specify a library file.  These
  default libraries are searched after any libraries specified on the
  command line (with /LIBRARY) and before the system-supplied library
  FORSYSDEF.TLB.  It can have multiple translations; each translation
  is used as if it appeared as an input file on the command line with
  the /LIBRARY qualifier with file specification defaulting occurring
  within the FORT$LIBRARY list only.