Should our bracket measurements be taken after unclamping?

Had a fitter show me a lovely bracket once, still bolted to the fixture. Couldn't put it on the mating plate after we freed it. Very lovely fixture, though. Start with the drawing's measurement conditions. If it doesn't specify restraint, don't quietly add the clamps to make the numbers work. You can still measure fit-up and the clamped assembly to understand what's moving; label those separately from the final part check. Also ask how long the old parts had cooled before those released measurements. That missing detail can waste a lot of arguing.