What defines the 'controlled braking' method of making an emergency stop with air brakes?

AAMVA CDL Manual, Section 5, subsection 5.4.3, p. 5-8; 49 CFR 383.111(b)(7)(iii) (Emergency stops)

Controlled braking lets a driver stop as quickly as possible while still being able to steer around an obstacle, which stab braking sacrifices during its release phase. Choosing the right method, and knowing the steering limitation it requires, is directly tested on the air brakes knowledge exam and matters in a real roadway emergency.