Library /sys$common/syshlp/basichelp.hlb Compile time errors, ILLOPEARG  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  ERROR - The program performs an operation that  is  inconsistent  with
  the  data  type of the arguments, for example, an arithmetic operation
  on variables of the RFA data type.  Remove the operation or change the
  data type of the arguments.