Congratulations on finding the word you were looking for. The only problem is, when you use WebDAV, the payloads aren't hypertext. The acronym doesn't matter.

Tar stands for tape archive, but thankfully it works on disk drives too.

If I download a Debian .iso using HTTP, is that hypertext? How about updating my system using `apt`?

It's called that, but the program in question doesn't understand it. The fact that the protocol's name contains "hypertext" is irrelevant, just as using http to download a .zip file doesn't make that file a "hypertext".