[Timothee]

I've seen that kind of nomenclature only on sites like Monster or Salary.com and I've always felt similar as your comment: where do these come from? How come I was never told about it? How come my positions were never classified like this?

Overall, for me, it falls under these semi-established things that you're supposed to learn somehow. Some people know what it is and will make sure that their jobs are classified a certain way. Of course, since I don't know, I'm biased, but I feel that employers and employees that use them are probably not good cultural matches for me.