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
So, as a technical writer, this is an issue that comes up for me quite regularly when reviewing other people's work, whether it be programmers, BAs or other writers. Typically, id refers to ego as others have said before me and the accepted abbreviation for identification is ID, just because plenty of people don't know or understand the rule doesn't mean that they are correct (sorry to be blunt), mind you the rules for punctuation and spelling to a large degree are almost as changeable as fashion!
However, what no-one seems to have asked is, does your company have a standard? At the end of the day if your company has a style guide and they have covered this topic in that guide, you should follow the guide. If it is not covered, then may I suggest that you raise the issue with the person that maintains the guide and include any stakeholders in the conversation. Consistency is key here. If the company you work for doesn't have a style guide, then perhaps it is time to start one!
Hope this helps...