xAP promotes the use of common data definitions wherever possible. Commonly encountered elements - caller id information, X-10 control messages and so on - can be represented using standard schema. A device intercepts and acts on messages. A message comprises one or more message blocks. The semantics of a specific message block are determined by the schema.
A xAP class is a pre-defined collection of message blocks (or schema) to be expected in the message body. It effectively defines the structure of the entire message in terms of message blocks. Schema represent entities that are commonly encountered in the home control environment - such as temperature, phone numbers, device status and device control. These entities can be used in many different contexts. A class defines a context within which one or more schema are applied.
xAP identifies the schema that applies to a given message through the "class" keyword in the message header.
For a complete description of the xAP message format, see the xAP Specification.
Basic Status and Control
Dialup Internet Connection Monitoring
CallerID and Meteor Extensions
Audio and Media Control
On Screen Display (OSD)