Input Event Mapping: Tweak. What do the different event types do?

Hi guys,

Sorry, beginner question but I searched and couldn’t find an answer.

In User Preferences>Input you can set your event mapping to Tweak which lets you click/drag selections, transforms, etc.

In messing around with the Type of Event (ie. Select, Action) I’m not seeing what the different types do. Sometimes changing a mapping from Select to Action causes the function to stop working, sometimes not.

Can anyone explain what the different types do and how to use them, or where I can find the info in the docs?