Novices, all Primary Classes, and most Expanded Classes (except for Super Novice) have extra progression beyond just their Skills and Job Levels: once you reach a certain specific Job Level and allocate all of your Skill Points, you have the option to evolve into a new class. When you do so, your Job Level is reset to 1 (you don't lose any of your already-existing Skills and Skill Points) and you get access to entirely new Skills plus extra bonuses to your Stats. Progression goes as follows: