MDB_CALLB_PROMPT
(void) mdb_callb_add(NULL, MDB_CALLB_PROMPT, (mdb_callb_f)prompt_update,
ASSERT(class == MDB_CALLB_STCHG || class == MDB_CALLB_PROMPT);
ASSERT(class == MDB_CALLB_STCHG || class == MDB_CALLB_PROMPT);
mdb_callb_fire(MDB_CALLB_PROMPT);