One of the many fascinating things about reading early RPGs is discovering peculiarities in their vocabularies. For example, lots of people have commented on the use of the word "throw" for "roll" in games like Empire of the Petal Throne and the Holmes-edited Blue Book. In between all my Dwimmermount writing, I came across another one.
I've been reading my copy of The Complete Warlock, published in 1978 by Balboa games explicitly as "a major D&D variant." The Complete Warlock is a codification of house rules that originated at the California Institute of Technology in 1975, making it one of the earliest variants of OD&D and thus a window on the dawn of the hobby.
While I'll have more to say about Warlock soon, one of the things that struck me about it was its use of percentile dice, which it calls "00-99" dice. What a strange formulation! Equally strange (to me anyway) is that the rules consider a result of "00" as the lowest possible result, below "01." In combat, for example (which uses a percentile system), a roll -- or should I say "throw?" -- of "00" is always a hit, while a roll of "90-99" is always a miss.
It's a small thing, admittedly, but completely contrary to my own experiences. In the Blue Book, there's a section on how to use dice and it explicitly identifies as a roll of "00" as being "100." That's why pretty much every game I ever played back in the day did it, but then I didn't start playing till late '79, by which point even D20s numbered 0-9 twice were already fading into the mists of history.