OK excuse the double post.
Here's what I did
I emptied layer1 and I emptied Alt2 layer.
I then moved everything in layer2 into layer1
I then duplicated the 122FlrCOL raised it and had a play with the planes basically deleted some of the internal edges and vertexes and put in new ones.
I reset the Normals to outside then Exported. as per Testing your shell. I also backed up Phats_District_Shell122.prp before installing.
I was doing well till I came to running PlasmaShop (remember this is a age writing noob here) I eventually figured out I needed to add the game to PlasmaShop this is not mentioned in "Testing Your Shell" in the wiki so that's another thing to add to my Newbie starter kit.
But I did the checksum thing and there was no Python so nothing to do there and Prad was allready in ULM so lets go test.
- Show Spoiler
OK who nicked my shell. Oh yes that would be me wouldn't it.
But the weird thing is the floor is still there to run on so my conclusion is 122FlrCOL is the floor collision detect. (can somebody correct me if I am wildly wrong).
Anyway I retrieved my previous Phats_District_Shell122.prp from the backup re did the checksum with PlasmaShop and everything is back.
But I am no closer to the answer to my previous post.