3.4.4 Message Processing Events and Sequencing Rules
When a client object issues an object activation, the client MUST specify a partition ID in the guidPartition field of the SpecialPropertiesData structure ([MS-DCOM] section 18.104.22.168.2). The specified partition ID MUST be ONE of the following:
GUID_NULL, to request that the server select a partition for the client.
The partition ID associated with the client object context.
The ID of the partition that the client requires the server object to be configured in.