What is the term for this grating, this blood-curdling, this ghastly habitual use of emphatic auxiliary verbs?

I've always called this do + verb periphrastic construction the emphatic mood. (It doesn't bother me as much as it seems to you.) It's interesting that do is more or less required in present-day English when constructed the unmarked negative indicative: I write books, I don't write books (~ I write not books). I have a friend who habitually uses this construction instead of the simple past tense: I did read that book. It used to confuse me, until I realized he probably picked this up while learning English in school as a way to avoid past tenses of irregular verbs. (I have since noticed other Germans using this construction.)

Ceci n'est pas un seing.