TomE is now providing a PDF of what he terms an "electronic album sleeve" for Op 1.1. This is an interesting twist, and in some sense a welcome throwback to the 1980s, when Severed Heads would send you booklets for $5. These booklets - I still have all of 'em moldering in a box somewhere - still strike me as unique in the annals of pop music. I suppose you could say it's the only open source music out there; they contained all the technical information you'd want, such as what instruments and objects were used, and also contained helpful tips for making your own.
The only thing I can think of that comes close is [The User] - the 3" CD of their Symphony for Dot Matrix Printers contains the text files used in the recording on a data track on the CD. Sadly, this went missing on the 5" reissue.