I agree with what you wrote except for processing instructions: I’m using them in an XML tool I’m developing for my own use, and while I could devise ways to en

I agree with what you wrote except for processing instructions: I’m using them in an XML tool I’m developing for my own use, and while I could devise ways to encode them in other ways by abusing other syntax such as namespaces or (ugh!) comments, I prefer to have them available, indeed to be used sparingly.