See Switcher API Overview for background information.

  Switcher API    INT 2fH 4B01H  Build Notification Chain
INT 2fH 4B02H  Is Switcher Installed? / Get Service Addr
INT 2fH 4B03H  Allocate Switcher ID
INT 2fH 4B04H  Free Switcher ID
INT 2fH 4B05H  Identify Instance Data

       Services    SwSrvcFn 0000H Get Switcher Version
SwSrvcFn 0001H Test Memory Region
SwSrvcFn 0002H Suspend Switcher
SwSrvcFn 0003H Resume Switcher
SwSrvcFn 0004H Hook Notification Chain
SwSrvcFn 0005H Unhook Notification Chain
SwSrvcFn 0006H Query API Support

  Notifications    SwNtfyFn 0000H A Switcher Is Being Initialized
SwNtfyFn 0001H Can Switcher Please Suspend Your Session?
SwNtfyFn 0002H Switcher Is Suspending Your Session
SwNtfyFn 0003H Switcher Is Activating Your Session
SwNtfyFn 0004H Session Is Now Active
SwNtfyFn 0005H Switcher Is Creating a Session
SwNtfyFn 0006H Switcher Is Destroying a Session
SwNtfyFn 0007H Switcher Is Exiting

  Structures    SwApiInfoRec

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Switcher API