Hm no, I don’t think so. That’s a piece of the plugin that came straight over from the Drupal module. Here’s where they are defined in the code, though.

Then that variable gets set to one of the values like this:

• if it’s a pull
• if it’s a push

I wouldn’t necessarily object to putting documentation in for them if someone put in a pull request. I’m inclined to think it’s developer level stuff and someone should be writing code already if they’re using those values, though.