Delivery of scan services of a networked scanning device over a device service port interfaced to the network. An extended XML schema is comprised of an extension to a baseline XML schema which defines baseline functions exposed by the scanning device via the device service port together with baseline parameters for such functions. The extension defines an additional parameter for a predesignated one of the plural baseline functions. A scan job is created by transmission of a request to create a scan job over the device service port. A request for scanner functionality defined by the predesignated function is transmitted to the scanning device via the device service port, with a non-null value specifying a device command for the additional parameter. Data responsive to execution of the device command by the scanning device is transmitted to the client via the device service port.