Checks the completion status of a system service that completes
    asynchronously.

    On Alpha and Integrity server systems, this service accepts 64-
    bit addresses.

    Format

      SYS$SYNCH  [efn] ,[iosb]

    C Prototype

      int sys$synch  (unsigned int efn, struct _iosb *iosb);

  Additional Information (explode) :

• Arguments