AG2 numbers are used to identify medals rolls. The AG2 number is written on top of a stamp, usually in the left corner of medal rolls to mark significant sections.
This is what a close-up of a stamp looks like:
This example is taken from the first page of the 10th Hussars roll (WO100/116p109). In this case, the reference is AG2/M/2998.
If another roll wants to reference this section of the 10th Hussars' roll, you will see AG2/M/2998 used in the other roll.
The following table allows you to search all the AG2 references to identify the unit connected to that number or to find all the numbers relating to a unit:
The list of AG2 numbers of not complete so please add a comment if you identify a missing number so that it can be added to the list.