"Installed"
Following your logic Skybob, surely re-issuing the Flight Plan with the statement "TCAS not installed" is not correct.TCAS is INSTALLED but just today (and possibly for 10 more days) it is simply INOPERATIVE.So your flight plan can say perhaps "TCAS installed but is temporarily U/S"?
An interesting aside is the definition of "DISPATCH".One poster said "you have dispatched once your aircraft moves under its own power".However in some countries this definition is "once applying thrust for takeoff".