>> Some older/obscure ones: Cse, Cxi (or just x, i).
I believe that these would traditionally be DeskJet models.
C represents "Color", and the se, xi, x or i represents either the software bundle or the reseller.
For example, Staples used to sell the DeskJet 722Cse, whereas OfficeMax or Office Depot was selling the 722Cxi.
Same printer, different vendor, and possibly slightly different software bundle inside.