The $ACM service provides a common interface to all functions
    supported by the Authentication and Credentials Management (ACM)
    authority. The caller must specify the function code and any
    applicable function modifiers and item codes for the requested
    operation.

    The $ACM service completes asynchronously; for synchronous
    completion, use the $ACMW form of the service.

    Format

      SYS$ACMW  [efn], func, [context], itmlst, acmsb, [astadr],

                [astprm]

    C Prototype

      int sys$acmw  (unsigned int efn, unsigned int func, struct

                    _acmecb *context, void *itmlst, struct _acmesb

                    *acmsb, void (*astadr)(__unknown_params), int

                    astprm);