1. A markup post-processing device comprising: a program input operable to receive a markup processing program containing a set of markup processing instructions that, when executed in the markup post-processing device, carry out application of one or more expressions on streaming data represented by a markup language representation, each markup processing instruction including an operation defining a processing operation to be matched to the markup language representation and a corresponding action to be performed upon matching the operation to the markup language representation; a markup input operable to receive the markup language representation containing encoded items representative of markup language constructs; and a microsequencer coupled to the program input and the markup input, the microsequencer operable to execute the markup processing program, in real-time, to the streaming data in conjunction with the markup language representation to dynamically control generation of an output control signal from an output of the microsequencer to indicate how the markup language representation is to be processed for generation of output based on the markup language representation; wherein: the markup processing program is applied in real-time in hardware to streaming XML data represented by the markup language representation; the markup processing program represents a compilation of instructions programmed that, when executed in an embedded hardware markup post-processing device, carry out application of one or more XPATH expressions on the stream of XML data; and the operations of receiving the markup processing program, receiving the markup language representation and executing the markup processing program are performed by the embedded hardware markup post-processing device such that software applications operating in conjunction with an operating system in a computerized device in which the which the markup post-processing device that provide the one or more XPATH expressions do not have to apply and evaluate the one or more XPATH expressions against the markup language representation.