One helpful set of terms is essential vs. nonessential. When the identifier makes sense in the sentence by itself, then the name is nonessential and you use a comma before it. Otherwise, no comma. That explains an exception to the only-thing-in-the-world rule: when the words “a,” “an” or “some,” or a number, come before the description or identification of a name, use a comma.
What would be some examples using "some" or a number ?
What about these examples using one comma? Is this usage incorrect?
The branch would like to thank mayor, cllr Jane Smith for her generous work.
Volunteer, Lucy has set out to arrange a charity run.
Jenny and her partner, Steven would instead be attached as potential owners.
So any description or identification before a name requires that name to be set off with commas?