Commenter Yuhong Bao asks, "Do you know that the Novell behavior described in "Not all short filenames contain a tilde" came from HPFS?"

Yes, but it was not relevant to the discussion so I didn't bother mentioning it. Going into more detail on the history of the Novell "long namespace" would just encourage people to conclude, "This problem affects only Novell, and since I don't use Novell, I don't have to worry about this."