14.2  $CLEAR_SYSTEM_EVENT

  Clear System Event

  Clear Event does not allow you to specify a handle and an
  event.  You must pass a zero as one of these parameters.  You
  can either clear by handle or request that all events for the
  user be cleared.

  Removes one or more notification requests previously estab-
  lished by a call to SYS$SET_SYSTEM_EVENT.

  Format:

  SYS$CLEAR_SYSTEM_EVENT [handle], [acmode], event

  C Prototype:

  int sys$clear_system_event (struct _generic_64     * handle,
  unsigned int acmode, unsigned int event);

  Arguments:

  handle

  OpenVMS usage:               identifier
  type:                        quadword (unsigned)

  access:                      read only
  mechanism:                   by reference

  Identification of the AST request to be cleared.  The  han-
  dle argument uniquely identifies the request and is returned
  when the $SET_SYSTEM_EVENT service is called.  The
  handle   argument may be omitted by specifying a zero
  address.

  acmode

  OpenVMS usage:               access_mode
  type:                        longword (unsigned )

  access:                      read only
  mechanism:                   by value

  Access mode of the system event to be cleared.  The    acmode
  argument is a longword containing the access mode.  The
  value of the access mode is maximized with the access mode
  of the caller.

  event

  OpenVMS usage:               event_code
  type:                        longword (unsigned)

  access:                      read only
  mechanism:                   by value

  The  event  argument is a value indicating the type of sys-
  tem event to be cleared.  SYSEVT$C_ALL_EVENTS may be
  specified to clear all event types.

  Description

  The Clear System Event service removes one or more event
  types or notification objects previously established by a call to
  the $SET_SYSTEM_EVENT service.

  A valid request specifies either the  handle   for a specific
  notification request, or is a wildcard clear of all notifica-
  tion objects whose is access mode is greater than or equal to
  acmode    .

  If the handle   argument is specified, caller's access mode
  must be less than or equal to the access mode of the object to
  be cleared.

  If SYSEVT$C_ALL_EVENTS is specified, or the set of events
  enabled for the object(s) becomes empty, the notification object
  is deleted.

  Required Access or Privileges

  None

  Required Quota

  None

  Related Services

  $SET_SYSTEM_EVENT

  Condition Values Returned

  SS$_NORMAL                   The service completed successfully.

  SS$_ACCVIO                   The service cannot access the location
                               specified by the handle.

  SS$_BADPARAM                 One of more arguments has an invalid
                               value, such as an invalid handle.
  SS$_NOSUCHOBJ                No request was found that matches
                               the description supplied