2.2.2.21 PidTagAttachAdditionalInformation Property
Type: PtypBinary ([MS-OXCDATA] section 2.11.1)
The PidTagAttachAdditionalInformation property ([MS-OXPROPS] section 2.585) MUST be set to an empty string if the PidTagAttachEncoding property (section 2.2.2.20) is unset. If the PidTagAttachEncoding property is set, the PidTagAttachAdditionalInformation property MUST be set to a string of the format ":CREA:TYPE", where ":CREA" is the four-letter Macintosh file creator code, and ":TYPE" is a four-letter Macintosh type code.