This standard specifies a directory index to classify various types of data to be recorded into the binary groups (user bits) of the SMPTE time and control code. The directory index, located in two binary groups of the time and control code frame, fully specifies the type of data stored in the remaining binary groups of that frame.

This standard also specifies the group assignments of timing, application, and control data types to subsets of the directory index. It applies to both linear and vertical interval time code applications. Specifications of application dialects will be developed in related documents.