It looks like a sort of serial number or categorization. The first block they are T1. The second block they are T2. So each category (access, persistence, etc)

It looks like a sort of serial number or categorization. The first block they are T1. The second block they are T2. So each category (access, persistence, etc) is a T w a leading number and the issues/“tactics” inside of that have a 001, 002 etc, as a reference to that specific instance (meeting overload) Edited for typos