All the Operator's Manual is going to say is "There are 2 buttons on the top and 3 on the side, the function is dependent on how they're programmed." The Orange one is usually programmed for Emergency.
Just like on your XTS5K, you can program the buttons to whatever you want, and the functions can differ between trunked and conventional operation.
If you have a specific question, Iike Luis_R said, I'm sure there are lots of us here who'd be happy to try to help. But those operator manuals are just about the most empty things I've ever seen.
Peter
K1PGV