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Property Keys

Programmatically, all device properties in the unified device property model are represented by property keys. The property keys are coded as DEVPROPKEY structures. The property keys are defined in Devpkey.h.

A DEVPROPKEY structure has the following members:

fmtid

A DEVPROPGUID-typed variable that identifies the property category.

pid

A DEVPROPID-typed variable that is the property identifier. For internal system reasons, a property identifier must be greater than or equal to two.

To create a custom device property key, use the DEFINE_DEVPROPKEY macro.

The following is an example of how to use the DEFINE_DEVPROPKEY macro to create a DEVPROPKEY structure. The name of the structure is "DEVPROPKEYStructureName", the sequence of values 0xde5c254e through 0xe0 supply the GUID value, and the value "2" is the property identifier.


DEFINE_DEVPROPKEY(DEVPROPKEYStuctureName, 0xde5c254e, 0xab1c, 0xeffd, 0x80, 0x20, 0x67, 0xd1, 0x46, 0xa8, 0x50, 0xe0, 2)

Note   The system-defined property key categories are reserved for system use only.

 

 

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