VMS Help CC, Language topics, Data Types, Void  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  You can use the void data type to declare functions that do not
  return a value.  Functions declared to be of this type cannot
  contain return statements and cannot be used in statements where a
  return value is expected.  The void data type can be used in the
  cast operation if casting to a "function without a return value
  ...".  You can also use the void data type with pointers.