$SET_DEVICEW

   Modifies the characteristics of a device or the paths used to
   access that device.

   The $SET_DEVICEW completes synchronously; that is, it returns to
   the caller only after the requested action has taken effect.

   Format

     SYS$SET_DEVICEW  [efn] [,chan] [,devnam] ,itmlst [,iosb]

                      [,astadr] [,astprm] [,nullarg]

   C Prototype

     int sys$set_devicew  (unsigned int efn, unsigned short

                          int chan, void *devnam, void

                          *itmlst, struct _iosb *iosb, void

                          (*astadr)(__unknown_params), int astprm,

                          struct_generic_64 *nullarg);