Crown CSC 835L Tape Bias

On the Crown CSC 835L there a switch that toggles between VHF Stereo - Mono - Wide when the Radio function is selected. When the Tape function is selected that same switch toggles between OSC 1-2-3. Now I believe this is something to do with tape bias, but does anyone know what 1-2-3 represent - for instance is 1 normal bias. Any help appreciated.

Damn. Looking at a few cassettes its for Type i - Type ii and Type iii - the 1-2-3 representation threw me. Well, at least a few of you will have had a laugh.

I thought the OSC functions were to be used for MW.

Beat cancel perhaps?

Hmm. Just looked at my Crowns and the stereo switches also have OSC. Not sure, but something to do with fm-sw-mw

The best I could come up with is oscillating stereo control, whatever that means.