:Jerome, I see you never got around to this…! I’m not surprised: I looked for an example of the ‘’in nomine’’ plainsong notaion and couldn’t find one online - to my astonishment too.  
 :But maybe you could clear up a question for me: is the cantus firmus of the English ‘’in nomines’’ the plainchant (in the alto part), or one of Taverner’s other three parts? This is not clear to me in the article. If the ‘’in nomines’’ are based on the plainchant, then where does Taverner come into it? Your expertise would be most appreciated, and maybe the article requires some explanation to this effect.