Gemini has East and West safety limits and a "Goto Limit".

West Safety limit
If the mount is tracking from east to west (the telescope is on the west side of the pier looking east) and it tracks into the West safety limit, Gemini will stop tracking and it will take operator interaction to move the mount out of the safety limit.

GoTO Limit
Because the Gemini mount can track well past the meridian, a GoTo limit is provided. When tracking east to west, any slew west of the GoTo limit will cause a flip. The default value of the GoTo limit is the West Safety Limit minus 2.5 degrees. This seems to correspond to ACP's East to West parameter.

East Safety Limit
If the mount is slewed from west to east while (the telescope is on the east side the pier looking west) past the Eastern Safety limit it will cause a flip. This appears to correspond to ACP's West to East parameter.

So far as I know, the Gemini Net driver implements both the SideofPier property (per Telescope1 spec) and DestinationSideOfOier method.

That is my story and I'm sticking to it

Jim Jones