Tell the TCS which instrument is in use. Format: INSTRUMENT <instrument\?name> Defaults: None. The parameters for ISIS are set on startup. Parameters: None. Keywords: Valid instrument names are: ISIS ISIS and FOS spectrographs. TAURUS Taurus imaging Fabry-Perot interferometer. MES Manchester Echelle Spectrograph. DURPOL Durham imaging polarimeter. AUXCCD Cassegrain auxiliary port CCD camera. UES Utrecht Echelle spectrograph. LDSS Low-dispersion survey spectrograph. PFCCD Prime focus imaging CCD camera. AUTOFIB Prime-focus automatic fibre positioner. OWN Spare for users' own instrument. Examples: INSTRUMENT ISIS Comments: This command sets the origin of position angle used for a specific instrument and the scale and orientation for the TWEAK command (). Position angle on the sky is normally defined to be along the slit in a spectrograph and aligned with one of the detector axes for an imaging instrument. The scale and orientation parameters are currently set to match the standard TCS xy coordinate system except for the LDSS keyword, where they correspond to the system used by the LEXT software package.