That example came along fast. I didn't expect an Anglo-American example (assumption based on links) and I wonder about the origin? The lack of a period makes it somewhat simpler for system handling, but I wouldn't bet on it sailing through without issue.
My father's middle "name" was a single letter. My grandparents didn't give him a middle name (at least not in English), but the nurse took it upon herself to record what sounded like a middle initial to her, and that's what ended up on his birth certificate. It stood for nothing but the letter itself.
I love it when I get asked that as a security question, only to be told it's invalid (too short). Tell that to Harry S Truman!