The IPIAppIdentity interface is a secondary interface supported by the PISDK object. The interface has a single property, Identifier, that can be set with a string. This string is used to identify the application to servers with which it connects. Typically the string will be contain a GUID in Registry format. The Server can compare this identifier against a list of known identifiers to provide feedback on the types of applications connected at any given time.
Only PI 3.3 SR1 and greater servers support this feature. Setting an identifier when connecting to older servers has no effect.