The LambSoft BRD file format was devised to store date from the Ascension Technologies "Flock of Birds" motion capture system. Although the suffix "BRD" implies that it is only for the Flock of Birds system this format is capable of storing data from any magnetic system.

Data from magnetic motion capture systems is different from data acquired from optical motion capture systems. With magnetic data there are fewer sensors but each sensor gives much more information. Magnetic systems are also real time, that is, the data can be fed from the motion capture hardware directly into the application that is receiving the data. Optical data generally has to be processed before any data is available.

With magnetic data each sensor reports its position and orientation at each sample. The sensors report their data in world coordinates where the magnet is considered to be (0,0,0) for the world coordinate system. The sensors report their information independent of the other sensors so they do not provide any kind of hierarchical information.