THE WEB SERVICE MODELING LANGUAGE WSML: AN OVERVIEW <s> Identifiers in WSML <s> {PG,1 A tractor draft load monitoring system responsive to tractor and associated implement load changes. The system is particularly adapted for a tractor having an engine/transmission power unit coupled to its drive shaft. The power unit is mounted on the frame by resilient mounts that permit measurable angular displacement of the power unit relative to the frame about the drive shaft axis in reaction to changes in the drive shaft torque. The working depth of the implement, which may be tractor mounted, semi-mounted or a pull type implement, is raised or lowered by a hydraulic lift system that is controlled by a control valve assembly connected to a source of fluid under pressure. Interposed between the power unit and the control valve assembly is a transmission cable (Bowden wire type) and lever system that is operative to transmit angular displacement of the power unit to an actuating member of the control valve assembly to cause hydraulic actuation of the hydraulic lift device to change the working depth of the implement to compensate for changes in its draft load. <s> BIB001 </s> THE WEB SERVICE MODELING LANGUAGE WSML: AN OVERVIEW <s> Identifiers in WSML <s> Abstract The OWL Web Ontology Language is a new formal language for representing ontologies in the Semantic Web. OWL has features from several families of representation languages, including primarily Description Logics and frames. OWL also shares many characteristics with RDF, the W3C base of the Semantic Web. In this paper, we discuss how the philosophy and features of OWL can be traced back to these older formalisms, with modifications driven by several other constraints on OWL. Several interesting problems have arisen where these influences on OWL have clashed. <s> BIB002
WSML has three kinds of identifiers, namely, IRIs, sQNames, which are abbreviated IRIs, and data values. An IRI (Internationalized Resource Identifier)  uniquely identifies a resource in a Web-compliant way. The IRI proposed standard is the successor of the popular URI standard and has already been adopted in various W3C recommendations (e.g.,  ). In order to enhance legibility, an IRI can be abbreviated to an sQName, which is short for 'serialized QName', and is of the following form: prefix#localname. The prefix and local part may be omitted, in which case the name falls in the default namespace. Our concept of an 'sQName' corresponds with the use of QNames in RDF and is slightly different from QNames in XML  , where a QNames is not merely an abbreviation for an IRI, but a tuple <namespaceURI, localname>. Data values in WSML are either strings, integers, decimals or structured data values. Structured data values are constructed using datatype wrappers. Each datatype has a datatype wrapper associated with it. Datatype support in WSML is based on XML Schema, and WSML defines constructs which reflect the structure of data values. For example, the date "March 15th, 2005"is represented as: date (2005, BIB001 BIB002 . In logical expressions, constructed data values can be used in the same way as constructed terms, with the difference that constructed terms may not be nested inside constructed data values.