Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
program (n., v.)
Americans spell the noun and the infinitive of the verb with one m; other forms of the American verb are in divided usage: programed or programmed, programing or programming. The noun with the agentive ending is similarly divided—programer or programmer—but the adjective programmable always has two m’s, and Americans usually use the two m’s when the subject is programmed instruction or computer programming. The British spell the noun and verb programme and consistently spell the other forms of the word with two m’s. See CONSONANTS (2); SPELLING (1).
