Anything that goes with saying is something that someone will go without.
Read Glen Alleman’s post on marking progress to plan. I want to focus on the “What does done look like?” part about meeting operational paramters.
That the product has to work is often implicit, rather than explicit. Glen’s statement makes it explicit. But you also well defined functional and non-adequate funtional specifications. (performance, security, uptime…)
I’ll take it one step further make it even more explicit, working means absense of major or extreme defects. By major I mean it can fail to satisfy functional or non-functional technical specifications. By extreme, I mean the kind of defect that makes me pull the battery out of my mobile phone. By this standard, a large fraction of the products I use regularlly are not “done”. IMO, shipping undone products (without explicit customer agreement) is unprofessional. In some domains, it is criminal.