2.2.3 Index Keys
An index key references a content index record or a scope index record.
The index key consists of
The index key string: A sequence of bytes with different meaning for each type of index key.
The property identifier: An identifier of a property that is referenced by index key.
When ordering for index keys is required, index keys MUST be ordered using default sorting order, unless otherwise noted, as follows:
The index key string ascending.
The property identifier as a DWORD (see [MS-DTYP]) ascending.