2.21 PropertySetStream

The PropertySetStream packet specifies the stream format for simple property sets and the stream format for the CONTENTS stream in the Non-Simple Property Set Storage Format. A simple property set MUST be represented by a stream containing a PropertySetStream packet.

The PropertySetStream packet usually represents exactly one property set, but for historical reasons, the DocumentSummaryInfo and UserDefinedProperties property sets are represented in the same stream. In this special case, a PropertySetStream might represent two property sets.

An implementation SHOULD enforce a limit on the total size of a PropertySetStream packet. This limit MUST be at least 262,144 bytes, and for maximum interoperability SHOULD<4> be 2,097,152 bytes.

ByteOrder (2 bytes): MUST be set to 0xFFFE.

Version (2 bytes): An unsigned integer indicating the version number of the property set (or property sets). MUST be 0x0000 or 0x0001. An OLEPS implementation MUST accept version 0 property sets and SHOULD<5> also accept version 1 property sets. This field MUST be set to 0x0001 if the property set or property sets use any of the following features not supported by version 0 property sets:

• Property types not supported for version 0 property sets, as specified in the PropertyType enumeration.

• The Behavior property.

If the property set does not use any of these features, this field SHOULD be set to 0x0000 for maximum interoperability.

Value	Meaning
0x0000	Version 0 property sets will be used.
0x0001	Version 1 property sets will be used.

SystemIdentifier (4 bytes): An implementation-specific<6> value that SHOULD be ignored, except possibly to report this value to applications. It SHOULD NOT be interpreted by the OLEPS implementation.

CLSID (16 bytes): MUST be a GUID (Packet Version) packet representing the associated CLSID of the property set (or property sets). If no CLSID is provided by the application, it SHOULD be set to GUID_NULL by default.

NumPropertySets (4 bytes): An unsigned integer indicating the number of property sets represented by this PropertySetStream structure. MUST be either 0x00000001 or 0x00000002.

Value	Meaning
0x00000001	This structure contains one property set.
0x00000002	This structure contains two property sets. The optional fields for PropertySet 1 are present.

FMTID0 (16 bytes): A GUID that MUST be set to the FMTID of the property set represented by the field PropertySet 0. If NumPropertySets has the value 0x00000002, then this GUID MUST be set to FMTID_DocSummaryInformation ({D5CDD502-2E9C-101B-9397-08002B2CF9AE}).

Offset0 (4 bytes): An unsigned integer that MUST be set to the offset in bytes from the beginning of this PropertySetStream structure to the beginning of the field PropertySet 0.

FMTID1 (16 bytes): If NumPropertySets has the value 0x00000002, it MUST be set to FMTID_UserDefinedProperties ({D5CDD505-2E9C-101B-9397-08002B2CF9AE}). Otherwise, it MUST be absent.

Offset1 (4 bytes): If NumPropertySets has the value 0x00000002, it MUST be set to the offset in bytes from the beginning of this PropertySetStream structure to the beginning of the field PropertySet 1. Otherwise, it MUST be absent.

PropertySet0 (variable): MUST be a PropertySet packet.

PropertySet1 (variable): If NumPropertySets has the value 0x00000002, it MUST be a PropertySet packet. Otherwise, it MUST be absent.

Padding (variable): Contains additional padding added by the implementation. If present, padding MUST be zeroes and MUST be ignored.