“ID” or “Id” on User Interface

Question

The QA manager where I work just informed me there is a bug in my desktop app due to the sign-on prompt being \"Operator Id\" when it should be \"Operator ID\". Her argument bei

Answer 1

I prefer Id because when used with other 2-letter text, it doesn't become a single all-caps word

Photovoltaics systems ... PVID (one word or 2?) PvId (much more clear).