This section specifies the attributes that appear in the TNEF stream, including the structure of the attributes, the message properties they map to, and any required conversions between them and message properties.
Each attribute is described by a level at which it applies (message or attachment), the attribute ID, the length of the attribute data, the attribute data, and a simple checksum. They are documented in the following sections in the form "attXXXX". For example, attSubject refers to the following:
attrLevelMessage idSubject Length 1*CHAR Checksum