UF_INIT
ASSERT(s & UF_INIT);
valid = (to & UF_INIT)? from == s->ud_prev: from & s->ud_prev;
{ UF_INIT, "being initialized", sf_init, UF_UNDEF,
{ UF_QUEUE, "queued", sf_queue, UF_INIT,
initialization_worked = set_state(new, UF_INIT);