pdo:
PDO::ATTR_DEFAULT_FETCH_MODE
PDO::FETCH_PROPS_LATE
PDO::FETCH_KEY_PAIR
Fetches a 2 column result set into an associated array. (Added in PHP 5.2.3)
spl:
CachingIterator::FULL_CACHE
CachingIterator::TOSTRING_USE_INNER
SplFileObject::READ_AHEAD
SplFileObject::READ_CSV
SplFileObject::SKIP_EMPTY