A page or sheet of paper (or the electronic equivalent on a computer screen) that a performer uses to record the patch control settings on a synth which does not have patch memory. Prior to the arrival of synths with patch memory, performers created a huge variety of methods and notations for recording patch settings. Two popular methods were "keyword and value", in which the performer wrote down an abbreviation for the parameter and then the knob or setting value, and the "grid system" where the performer drew a grid on a piece of paper and wrote parameter values into specific boxes (perhaps based on the signal flow, or the physical layout of the synth's front panel). For some popular synths, pre-printed patch sheets became available which were already marked with all of the possible parameters and write-in boxes for the value of each. Another method used by some performers was to simply take a Polaroid (instant camera) photo of the panel, although this could be fraught with problems depending on the angle, focus, and lighting. With a modular synthesizer, the performer has the additional problem of recording the signal routing in addition to knob settings.
Nowdays, a huge variety of pre-designed forms can be found on the Web, suitable for actual paper or in-computer storage (as e.g. an MS Word document) or both. The modern equivalent of the Polaroid method is to use a digital camera to photograph the panel, and without the expense (and mess) of Polaroid film, a number of close-ups of various parts of the panel can be taken to ensure that everything is captured.