Errh, patent law is sort of at the opposite side of my knowledge, especially as it applies to software and algorithms. I guess I know the theory of copyright law applied to code vs. algorithms, though I can't point to case law that supports my understanding. When it comes to patent law, it might as well be written in Sumerian.

This is a classic example of non-definition in law. Words are used in a special way yet rarely given adequate definitions: meanings are taken to be "self-evident" even when they are not, and you can't even get a majority opinion of meaning under the law. It appears that an "article" is a tangible thing (having mass), indeed probably one that is manufactured (since "articles or materials" would otherwise be redundant). However, the law is full of redundancies.

This BTW could be a case where a "style" question is reasonable for another SE (Law se) – if "article" has a special interpretation under the law, what is that interpretation? I would recommend trying to absorb Gottschalk v. Benson, so as to better articulate the question of interest.