I have a document dated 05/05/2012.
What should I say?
- Based on the document from 05 May.
- Based on the document from 5th May.
- Based on the document from 05 of May.
Different organizations, publications, and contexts will call for different style guidelines.
Wikipedia, for example, has international readership, and does not use ordinal suffixes, articles, or leading zeros, but allows free interchange of the month and day order, e.g.
Based on the documents from 5 May…
Based on the documents from May 5…
with the [month day] format probably preferred in America. Other styles can be used, but should be chosen based on what is appropriate for the audience.
While I believe there is nothing grammatically wrong with "05 May", I would suggest avoiding it on the grounds it is inelegant and the leading zero is redundant.
"5th May" would be the most traditional way to write this date. I have never seen "of" used in a written date, except in extremely archaic constructions such as legal contracts "signed and witnessed this 5th day of May 2012" (Parenthetically, I note that in English law this makes absolutely no difference to validity. Some lawyers find it difficult to move with the times, however.)
Modern businesses often use "5 May" (omitting the "th") - my previous employer had this form in their house style guide, and I favour this form as it seems to be clearer - although were I reading it out loud I would still pronounce it "fifth May" or "fifth of May").