Change the title of selected documents according to a RegEx

I am exploring the interface of DT3 and came across the (for me) new action

Tools --> Batch Process --> Execute script

I would like to use this to change the title of selected documents according to a fixed RegEx. Can I add a new script to the scripts listed there? And how does the script interface with the documents?

ps: I do know about the script “Rename using RegEx”, but I want to create a script which does always the same without inputting the RegEx.

Those are smart rule scripts. See Help > Documentation > Automation > Smart Rule Scripts.

Thanks. Will check it out.