2.2.3.2.2.1 Stream ID Equation

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For numerical named properties, the following equation is used:

 Stream ID = 0x1000 + ((ID XOR (GUID index << 1))) MOD 0x1F

For string named properties, the following equation is used:

 Stream ID = 0x1000 + ((ID XOR (GUID index << 1 |1))) MOD 0x1F

0x1F is the maximum number of property name to property ID mapping streams that the .msg File Format allows in the named property mapping storage.

For numerical named properties, ID, in the equation, is the name identifier.

For string named properties, ID is generated by computing the CRC-32 (cyclic redundancy check (CRC)) for the property's Unicode name identifier.<1> For more information on the CRC-32 algorithm, see [X25].