The scheme attributed to Rudd takes two lists that exist independently of each other, the seventy-two spirits of the Ars Goetia and the seventy-two angels of the Shem ha-Mephorash, and pairs them position for position: the first Goetic spirit against the first Shem angel, the second against the second, and on through all seventy-two. Neither source text asks for this. The Ars Goetia assigns no angel to any of its spirits, and the Shem ha-Mephorash, a much older Jewish angelology built from three-letter names extracted from a sequence of biblical verses, has no demonic counterpart of its own.
The effect of the pairing is to give each demon a specific angel understood to hold it in check, so that the demon of a given degree is set against, and restrained by, the angel of that same degree. Bael, first of the seventy-two, is paired with Vehuiah in this scheme, one of the clearest examples of the pairing at work. The pairing turns a list of spirits to be commanded into a list of spirits balanced against a countervailing power, which is a different kind of magical object from either source list alone.
The scheme had a long afterlife independent of the question of its own authorship. It travelled through the Sloane and Wellcome manuscripts, was picked up by later systematizers of the grimoire tradition, and remains the standard reference point whenever a modern practitioner or writer wants to set a Goetic spirit against a governing angel rather than treat the seventy-two spirits as free-standing figures with no counterweight at all.