VMS Help FORTRAN, Character Sets, FORTRAN  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  The Fortran character set includes the entire FORTRAN-77 Standard
  set plus the lowercase letters a through z (uppercase and lowercase
  letters are equivalent) and the following special characters:

     !    (exclamation mark)     <Tab> (tab)
     "    (quotation mark)       <     (left angle bracket)
     %    (percent sign)         >     (right angle bracket)
     &    (ampersand)            _     (underscore)

  All printable characters (those in the range 20(hex) through
  7E(hex), or A1(hex) through FE(hex)) can appear in comments,
  character constants, and Hollerith constants.