"Although the rules have been thoroughly play-tested over a period of many months, it is likely that you will find some part that seems ambiguous, unanswered, or unsatisfactory. When such a situation arises settle it amongst yourselves, record the decision in the rules book, and abide by it from then on. These rules may be treated as guide lines around which you form a game that suits you. It is always a good idea to amend the rules to allow for historical precedence or common sense--follow the spirit of the rules rather than the letter."
Chainmail by Gary Gygax and Jeff Perren, p. 8, 3rd Edition