[chc]

I think "works" can include digital artifacts — to my understanding, this was part of the Mozilla Foundation's rationale for exemption. But Mozilla's "public work" was the Internet as a free platform, not just some piece of software used by some unidentified group of people. Mozilla compared the Internet to a public road, and depicted its role in maintaining the Web as a free and open platform as being similar to ensuring that roads are well-kept and accessible to everyone.

Yorba's application appears to have been more along the lines of, "We make free software. Poor people can use free software and other programmers can learn from it." (I'm basing this on the IRS's response — I can't find a full copy of Yorba's application anywhere.) So I can kind of see why that appears less compelling from a "public works" perspective to the IRS.