Previously you could choose to use aXes-TS or aXes-TS2 as your run time execution engine, but you could not use aXes-TS2 as your RAMP Tools engine.
You can now choose aXes-TS or aXes-TS2 as your RAMP Tools engine.
That choice is made in the Server Definition tab: 
It is recommending that aXes-TS RAMP users consider moving to the standards compliant aXes-TS2 engine, away from the Internet Explorer dependent aXes-TS engine.
Note that you need to test your RAMP application after making this move.