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

  ERROR -  The  program  attempts  to  assign  a  value  to  a  function
  invocation.  For example:

       DEF FNA(A) = A^2
       FNA(3) = 9

  Remove the assignment statement.  You  cannot  assign  a  value  to  a
  function invocation.