What is MD still?

[Unregistered]

I know "MD" is an abbreviation for medical doctor. I want to know what article of a sentence MD is. It is separated by two comma, but why?

So again, in the sentence:
Jane Doe, MD, evaluated the patient for half an hour.

what article of the sentence is "MD?" and why is it separated by two commas as opposed to just one?

[pyoung]

Oh, sorry! I misread your post.

'MD' in this sentence is an appositive: a word or phrase that renames, modifies, or otherwise explains a noun sitting right next to it. Appositives are set off by commas to indicate their function.

I hope this is more useful,

Petra