Position switching is ``selected'' when using one of the following GO procedures: OffOn, OnOff or OffOnOff. The On or Off positions can be contained in either a single scan or in separate scans. For a position switched observation in the same scan the GO FITS SWSTATE keyword will be PSWITCHONOFF. For a position switched scan with the off and the on in different scans the GO FITS SWSTATE keyword will be PSWITCHOFF and PSWITCHON respectively.
N.B. It is possible to combine position switching with another type of switching such as beam or frequency switching. This modes are to be considered non-standard modes and are not strictly dealt with in the current GO FITS file specification. However, to attempt to preserve some information on what happened within the GO FITS file the SWSTATE FITS keyword will be set to PSWITCHONOFF, PSWITCHOFF or PSWITCHON while the SWTCHSIG keyword will indicate which beam or frequency switching scheme was used.