Purchase Order, Quote Request, and BOM are built in and can be edited but not deleted. Add your own (Invoice, Delivery Docket, Estimate, …) with the + New button.
Uppercase reads best on the masthead.
Auto-derived from the title on save. Identifies this doc type internally — templates reference this value.
Shown in parentheses next to template names — e.g. "Default Quote (Quote)".
Shown in the PDF preview window's title bar.
Small label next to the recipient name in the masthead meta.