Wow, that's actually all over the internet. I had to look it up. I was only aware of the commonly knowns A's and B's and O's. :\

It is curious that he hasn't shared his work story with you. ? Most people have stories to share whether good, bad or ugly about jobs, layoffs, lack of opportunities, injuries, disabling conditions, etc.
That doesn't sound like a closeness that is necessary for an emotionally intimate relationship.

What about him, keeps you staying attached to him?