Withough going into to much detail:
We go by Operational Deficiency Categories which are NATO standard. CAT 1 deficiency ship cannot sail. CAT 4 is basically nuisance (I've never even staffed one that I can recall).
If a system doesn't have an OPDEF attached to it then its availalbe to do its job with no restrictions. Interestingly enough you can have equipment that isn't working but you're still sailing because it doesn't impact the mission.
Otherwise we're basically just like what you stated. Its working as advertized, does it have an OPDEF, is it U/S (unserviceable).