The purpose of these is to provide some real-life test data that can be used to test Picard functionality against real MB data. I am going to use these for testing changes to format py code.

The purpose of having untagged files is to test the cluster / lookup functionality. You want these to remain untagged even if someone saves them when they have test tagged them, hence the gitignore.

The purpose of having tagged files is for regression testing - you can retag them and see if anything changes. Like other test data, you will want to update these if your change changes the tag data.