What do these mean in SO10 general text?

I came across a customer SAPscript form that I need to modify, but it has only one line in the window text, like this:

And when I open the Included text object in SO10, it has content like this:

I've never seen any general text like this, and have no idea how to interpret all this, to be able to make any changes.

Can someone please help me with:

• Where/how are these notations defined?
• How to interpret what each 'token' means?
• Is there any menu item or editor that understands and put these 'token' automatically?