John,

I believe it is just a color variation of #2025 "MacMillan (clan)" which has an also known name on the STA of "...Old Ancient" . I believe the MOM (I like that acronym as this is quite often the MacMillan variant people think of when they think of a MacMillan Tartan, the mother of MacMillans so to speak ) is essentially the same sett but in the Modern colors.

Matt, or Peter, or one of my more knowledgeable kinsman may have a better understanding of it though.

Thanks for asking. And yes, the people at Burnetts and Struth made me fax them proof that I was not you using a disguised voice before they would sell me the tartan!.