Second-stage beta

A second-stage beta is a beta with an external manifestation. It was at one time believed that a beta was an anomalous individual with a perceptual manifestation, rather than one that affected the world around him or her. When Hafidha achieved breakthrough (in Knock on Coffins), and gained the ability to affect computers without touching them, but did not convert to a gamma, this new classification was created.

Theories
Since Chaz achieved breakthrough in Refining Fire, there is much debate over whether he has become a second-stage beta or a gamma.