SRD rum came originally in 5-gallon ceramic jugs marked 'SRD', overstrength and to be cut before issue. It became the currency of both the army ranks and the navy lower decks, and many I know rue the day political correctness binned the rum ration (we can let our men get killed, by by god, we're not going to allow them drink!).
BTW Derek, you'll get the SECOND one I find. The first will accompany me to my grave.