/sys$common/syshlp/helplib.hlb FORTRAN, Error Messages, Compilation Errors, INVCHASOU  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  SEVERITY:  W

  MESSAGE TEXT:  Invalid character treated as blank

  EXPLANATION:  A nonprinting character was found in a source line
  and was replaced by a space (blank) character.  The value of the
  last nonprinting character found in a source line appears within
  the message in the form [CHAR(nnn)], where nnn is the decimal value
  of the nonprinting character.

  For more information on valid nonprinting characters in source
  files, see your user manual.