Map Definitions control the conversion of field values (eg. Trace Headers) when mapped from one binary format to another. These Definition names are prefixed with "map:". Users can use these Definitions to override the default mappings between different formats. (NOTE: Trace Headers that do not change names always get mapped implicitly.)

There are several other special type of mapping-related Definitions. "read:" and "write:" Definitions are used to modify Trace Headers as they are read or written. Another Definition, "rename:", is used to rename a Trace Header when mapping between different binary formats.