Is "set" a noun or a past participle here?

[NewHopeR]

Context:


You also claim that I am making up my own definitions of plagiarism and copyright infringement. I insist on pointing out with regard to this question that the criteria I am using in accusing you of plagiarism and copyright infringement are not something I have made up. Every major journal and every educational institution has guidelines regarding these points, all of which are very similar. If Chinese scholars, such as yourself, expect to participate in the worldwide culture of science, you must learn to abide by the standards set forth in these guidelines. I have attached one such set from the American Chemical Society. You will note that not only do YOU not have the right to reproduce my article, even I do not have the right to use more than 400 words from my own publication, nor can I use my own illustrations, without written permission from the journal. Copyright not only protects the author of a work, but also the publisher of that work! This raises a point that has not yet been discussed in our correspondence, which is that you have not only plagiarized and/or breached the copyright on my article, but also Oxford University Press, which published the book in which my chapter appears. Did you get their written permission to use my material?

[5jj]

... you must learn to abide by the standards set forth in these guidelines. I have attached one such set from the American Chemical Society.

It is one set (noun) of guidelines.