There is an inconsistency in the way we describe locks when returned from currentOp(), as an example. According to http://docs.mongodb.org/manual/reference/method/db.currentOp/#currentOp.locks the ^ specifies database level lock, as in:

"locks" : {
    "^connectors_celery" : "W"
},

but according to http://docs.mongodb.org/manual/reference/method/db.currentOp/#currentOp.lockStats the capital "W" means global level lock. This was raised by a customer who was asking about updateAndModify – we know that we do not take a global lock on updateAndModify, so the documentation is wrong