A document was prepared describing the user requirements for a Standby Spectrograph and Camera (SCS) to be mounted permanently at a folded Cassegrain focus.
The general requirement is to provide an instrument with the same general capabilities as currently provided by ALFOSC. The new instrument should fit in the area current occupied by the adapter between the main telescope structure and the Cassegrain focus such that it is always available while an other instrument can be mounted at the Cassegrain focus. The general idea is to have a largely fixed instrument set-up with as little changes as possible. In principle the plan is to have the near-infrared camera and spectrograph NOTCam permanently mounted at the Cassegrain focus.
See for details:
http://www.not.iac.es/instruments/development/SCS.pdf