Memcache
PHP Manual

Constantes pré-definidas

Memcache Constants
Name Description
MEMCACHE_COMPRESSED (integer) Used to turn on-the-fly data compression on with Memcache::set(), Memcache::add() e Memcache::replace().
MEMCACHE_HAVE_SESSION (integer) 1 if this Memcache session handler is available, 0 otherwise.
MEMCACHE_USER1 (integer) Used to turn user-defined application flag on with Memcache::set(), Memcache::add() e Memcache::replace().
MEMCACHE_USER2 (integer) Used to turn user-defined application flag on with Memcache::set(), Memcache::add() e Memcache::replace().
MEMCACHE_USER3 (integer) Used to turn user-defined application flag on with Memcache::set(), Memcache::add() e Memcache::replace().
MEMCACHE_USER4 (integer) Used to turn user-defined application flag on with Memcache::set(), Memcache::add() e Memcache::replace().

Memcache
PHP Manual