Feature code
A 32-bit unsigned integer that represents a code specifying a feature.
Overview
The third field is the feature code, or name, a 32-bit unsigned integer that is usually best interpreted as four ASCII characters. Example: the maximum video bit rate feature has a feature code or name of 'mvbr'. It is permissible to use a feature code value of zero (0x00000000, not four ASCII zero characters) as a placeholder in one or more name-value pairs. The reader should ignore feature codes of value zero.