Cabin Sole joints

When removing the cabin sole from my '85 35-3 I found some sticky tape like substance at all the joints where 2 different pieces of the plywood butted up against each other. Can anyone tell me the purpose of this? Reduce squeaking? I would think this might cause the joints to rub together more than if the sole was just screwed down like it was everywhere else.

Should I use something in it's place under my new sole? What was it and where can I get similar?

Tha cabin sole on our E33 didn't have anything like this on the joints between sections.
However, one thing of note was that the joints where plywood sheets butted against one another were undercut with the saw just outside of square to help insure that the top veneer surfaces were in contact rather than the lower surfaces