Ratings
Below you will find links to the explanations for the various types of ratings.
A special note about Burglary and Lock Ratings: Many of the burglary and lock rating are matched to each other. For example, it is recommended to use a Group 2 lock on a B/C rated or RSC rated safe. Putting a higher rated lock (Group 2M, Group 1 or Group 1R) on a lower rated safe won't necessarily increase the security of the safe since the safe itself isn't designed for that level of security. Of course, it's also not recommended to put a lower rated lock on a higher rated safe and in many cases doing so will void the rating on the safe. For example, U.L. specifies that a TL-15 have no less than a Group 2M lock, so putting a Group 2 lock on it will void the TL-15 rating.