This feature was add a little while back I think about the AX2012 R2 release. It might be useful for some users who need to manage production orders and planned orders and working with a few documents you are trying to troubleshoot. The selection list gives you the ability to add interesting documents to a list so you can come back to them. You have to turn this feature on through the configuration keys but this is a quick walkthrough of what this looks like.

Cheers

Lachlan