2.3.3 Property Context (PC)
The Property Context is built directly on top of a BTH. The existence of a PC is indicated at the HN level, where bClientSig is set to bTypePC. Implementation-wise, the PC is simply a BTH with cbKey set to 2 and cbEnt set to 6 (see section 220.127.116.11). The following section explains the layout of a PC BTH record.
Each property is stored as an entry in the BTH. Accessing a specific property is just a matter of searching the BTH for a key that matches the property identifier of the desired property, as the following data structure illustrates.