I dont know this function, could you discribe please what it does. You could offset a fixture in the edit fixtures menu, eg, a fixture had been hung 90° degrees rotated to its normal orientation, so you do only an offset of 90° in the edit fixture window and all your positions are correct again. Is this what you are looking for?
On Chamsys you can program a global offset for all parameter you've changed... If someone hits a fixture on stage and moved that one, then you can correct the value of the preset in the active cue, hits the update button and choose "offset patch". All other pan/tilt preset are fixed now.
