The Wikipedia entry on First Normal Form also uses this kind of construction, which I suspect means it was written by the same person. I have never seen terms

The Wikipedia entry on First Normal Form also uses this kind of construction, which I suspect means it was written by the same person. I have never seen terms like domain and attribute used as if they were plurals (the way "data" is), but even were that correct, "a domain have" would be contradictory, so I think it is just a linguistic quirk of the writer.