Description

   When a process calls the vfork function, the resulting child
   inherits the parent's priority.

   With the DECC$ALLOW_UNPRIVILEGED_NICE feature logical enabled,
   the nice function exhibits its legacy behavior of not checking
   the privilege of the calling process (that is, any user may lower
   the nice value to increase process priorities). Also, when the
   caller sets a priority above MAX_PRIORITY, the nice value is set
   to the base priority.

   With DECC$ALLOW_UNPRIVILEGED_NICE disabled, the nice function
   conforms to the X/Open standard of checking the privilege of the
   calling process (only users with ALTPRI privilege can lower the
   nice value to increase process priorities), and when the caller
   sets a priority above MAX_PRIORITY, the nice value is set to MAX_
   PRIORITY.

   See also vfork.