Those show up if Max can find a .maxref.xml file for your abstractions.

For instance if you have MyAbstraction.maxpat, Max looks for MyAbstraction.maxref.xml

I can't find the documentation on how to make / format them on this site now, but if you dig around in the C74 bundle or anything you download via the Package manager you can use those as examples. They live in the "docs/" subfolder of most packages.

nvm, I just had a blank... I did this so many times! <facepalm>

The object in question didn't have any args but only one attr. And it needs to be set as get='1' set='1' in order to appear in the list when patching.

For anyone else reading this, Tyler probably meant this page.