Device Code for ENTER Button

I use a Sony RM-DX270 remote to control my CD players. It came originally with the 270 model. The remote has a section with Up Arrow, Down Arrow, Left Arrow and Right Arrow. In the middle is an ENTER button. I can't seem to locate a device file with the code for this button. In any file I can find that refers to this remote, the ENTER key is the one next to the numbers not the one inside the arrows and they of course are different codes.

Can anyone help me out? Thanks.