/sys$common/syshlp/helplib.hlb PASCAL, Attributes, Parameter, CLASS_NCA  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  The CLASS_NCA attribute causes a formal parameter to  be  passed
  by  a noncontiguous array descriptor.  This attribute is illegal
  on parameters of schema types.  This is  the  default  mechanism
  for conformant array parameters on OpenVMS Alpha systems.