The letter coding is as per DOD tool accountability and recoverability regulations in regard to third party supplier / local purchase / "government card" acquisition and ideally is a step that helps to prevent the card holder from stocking his garage up on uncle sams dime.
When the army uses a third party supplier for Class 2 items, It is a vendor requirement to be marked in this manner - otherwise they get dropped as a supplier in the DOD "SKO" program. (sets-kits-outfits). Yes, Uncle Sam has to play by different warranty rules.... Example: If an Army furnished Snap-On tool is unserviceable, the ARMY replaces the tool with like item via SKO, not snap-on.... The broken tool is then demilitarized and usually sold as scrap, exported, or sold as mixed lots via gov auctions.
Your socket was probably bulk/mixed lot purchased at a gov liquidation site... Since it is serviceable, the SKO site probably now furnishes an alternate toolkit meaning this item is classified by FEDLOG as obsolete, or "issue until depleted from inventory".
This is extremely common.
The barracks lawyers on here screaming "stolen property" should realize that these tools, being untracked (no serial number) are allowed an extreme leeway of being classified as being either a consumable item, or deemed a "field loss" at the slightest opportunity, sometimes as easily as the item was in use or not present at the time a property book inventory was being completed and therefore it was dropped from the property book.
Yep, it's a classic example of fraud waste and abuse, which the Military preaches about constantly.
Enjoy your socket!