The Broken Hourglass - Levels Explained @ Official Site

The Broken Hourglass site has an explanation of the leveling system.  Here's the intro they sent over:

In this week's Broken Hourglass game update, we explore the concept of level paths. Because point-buy systems can be intimidating, we provide a hybrid point-buy and class template system, which allows players to have the bulk of their experience points automatically spent along sensible class or occupationally-focused lines, while still leaving a reserve pool to preserve the flexibility of a point-buy system.