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This section lists the predefined string constants the UPnP AV Framework makes available for communicating changes to string-based state variables.

The UPnP AV DCP defines values for each state variable in a service. Some state variables can contain only certain strings. When the state variable changes, a device sets one of the allowed string values; a control point executes code based on these string values.

Code that uses the UPnP AV Framework can use these constants to help avoid interoperability problems and to create code that is easier to read.

To avoid name collisions, most of the constants are defined in unique C++ namespaces.

The following table shows the string constants, organized by the state variable(s) that use them.

Family Description

General String Constants

General constants that represent states valid for multiple state variables.


Contains the names of state variables evented by the AVTransport service.


Contains the names of state variables evented by the ConnectionManager service.


Contains the names of state variables evented by the ContentDirectory service.


Represents a storage medium for content.


Indicates how media is being returned by the transport.


Contains the names of state variables evented by the RenderingControl service.


Represents the ways that seek operations can be performed.


Represents transport actions, like play, stop, and so on.


Represents the state of a transport instance.

See Also