single word requests - What is the name for punctuation marks such as commas and periods that separate things like clauses or sentences?

Are you familiar with proofreading shorthand, a.k.a. editing marks? The figure below contains a small sampling of standard notations:

If you want to be more elaborate – such as when you want to express, "You need a comma or period here," – that may call for some inventiveness. For example, you could use something like:

Or, you could be even more general than that – I think this would do the trick:

I realize this doesn't answer your original question (looking for generic word such as delimeter), but it might solve your problem nonetheless.