Looking at the Community Faq for How do I correctly tag my questions?
- meta tags, tags that cannot stand alone as the only tag on a question, are not allowed.
[Note by MTibbits]: Personally I don't think this is a meta tag -- I added links and edited trying to keep the OP's intent -- but I still think it should be removed. I think id is ambiguous and should be removed to avoid many-to-one tag synonym relationships: e.g. global+unique+id=guid. See my answer below.