@MonicaCellio I added a sentence in each of the Machzor sections requesting a comment to this effect on each submission. This bit of copied information could make my job compiling easier, since it'll be one less thing to cross-reference when I'm putting things in order.

@MonicaCellio "No URL" sounds funny. "Account deleted" is quite descriptive, but sounds shady. In the Purim book, we used mi.yodeya.com/u/-1 for one such instance, user efrex.

@Scimonster The question already conceptually covers various practices by starting with "There are several things we don't do..." I think that there would be nothing wrong, both on MY and in the book, to add a second example to flesh out the question more. I also think there would be nothing wrong with not doing so.

@IsaacMoses sounds like a good idea, then. Thanks.

@IsaacMoses I suppose "N/A" is well-understood.

@MonicaCellio Yeah; probably better than any of the options I mentioned.