The Datatracker does officially support PPTX, so I don't believe it's
unreasonable to use it.
By "suipport" it, you mean "accept it and convert it to something
else," a meaning of "support" with which I'm unfamiliar. I'd say
"tolerate". What's worse is that if you post PPT/X, it gets converted
not to PDF, but to HTML, which I find awkward for slides (it's harder
to download a presentation as a whole in a convenient form). That's
why I do the PDF conversion up front.
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