# GML Overview This section describes how OS MasterMap Highways Network is defined in GML. An understanding of XML (Extensible Mark-up Language) and XML schema is required. GML is an XML grammar for expressing geographic features. GML serves as a modelling language for geographic systems as well as an open interchange format for geographic transactions on the Internet. More information can be found on the Open Geospatial Consortium (OGC®). The XML specifications that GML is based on are available from the World Wide Web Consortium (W3C): [http://www.w3.org.](http://www.w3.org/) Information about Unicode and UTF-8, the character encoding we have chosen, is available on the Unicode Consortium website: [http://www.unicode.org.](http://www.unicode.org/) ## Schema overview and location XML schemas are used to define and validate the format and content of GML. The GML 3.2 specification provides a set of schemas that define the GML feature constructs and geometric types. These are designed to be used as a basis for building application-specific schemas, which define the data content. The Path Network uses the following application schemas; **LinearHighwayNetwork.xsd, HighwaysWaterTransportNetwork.xsd, RoutingAndAssetManagement.xsd** and **OSProducts.xsd** which are referenced by the data. * The **LinearHighwaysNetwork.xsd** defines the features which make up the Path Network. Therefore, it imports the INSPIRE transport network road application schema. * The **HighwaysWaterTransportNetwork.xsd** defines the features which make up the Ferry Network. Therefore, it imports the INSPIRE transport network water application schema. * The **RoutingAndAssetManagement.xsd** defines the asset management features of the Path Network. Through the INSPIRE schemas both the **LinearHighwayNetwork.xsd HighwaysWaterTransportNetwork.xsd and the RoutingAndAssetManagement.xsd** import the GML 3.2 schemas. These in turn import schemas produced by the W3C, which are available from the W3C website at [http://www.w3.org/XML/1998/namespace.html.](http://www.w3.org/XML/1998/namespace.html) * The **OSProducts.xsd** defines the feature collection and feature members. In addition, this application schema will define the transactions used for a Change Only Update supply. The Linear Highway Network schema document defines the namespace, this is defined in the XSD at: [http://www.os.uk/xml/schema/highwaysnetwork/2.0/linearhighwaynetwork.xsd.](http://www.os.uk/xml/schema/highwaysnetwork/2.0/linearhighwaynetwork.xsd) The Highways Water Transport Network schema document defines the namespace. This is defined in the XSD at: [https://www.os.uk/xml/schema/highwaysnetwork/1.0/HighwaysWaterTransportNetwork.xsd.](https://www.os.uk/xml/schema/highwaysnetwork/1.0/HighwaysWaterTransportNetwork.xsd) The RAMI schema document defines the namespace. This is defined in the XSD at: [http://www.os.uk/xml/schema/highwaysnetwork/2.1/RoutingAndAssetManagement.xsd](https://www.ordnancesurvey.co.uk/xml/schema/highwaysnetwork/2.1/RoutingAndAssetManagement.xsd) The Highways Dedication schema document defines the namespace. This is defined in the XSD at: The application schema uses the following XML namespaces, for which definitions are available here: | **Prefix** | **Namespace identifier** | **Definition available at** | | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | gml | | | | xsi | [http://www.w3.org/2001/XMLSchema–](http://www.w3.org/2001/XMLSchema%E2%80%93instance) [instance](http://www.w3.org/2001/XMLSchema%E2%80%93instance) | Built in to XML | | xlink | | | | net | | [http://inspire.ec.europa.eu/schemas/net/4.0/Netw](http://inspire.ec.europa.eu/schemas/net/4.0/Network.xsd) [ork.xsd](http://inspire.ec.europa.eu/schemas/net/4.0/Network.xsd) | | tn | | [http://inspire.ec.europa.eu/schemas/tn/4.0/Comm](http://inspire.ec.europa.eu/schemas/tn/4.0/CommonTransportElements.xsd) [onTransportElements.xsd](http://inspire.ec.europa.eu/schemas/tn/4.0/CommonTransportElements.xsd) | | tn-ro | | [http://inspire.ec.europa.eu/schemas/tn-](http://inspire.ec.europa.eu/schemas/tn-ro/4.0/RoadTransportNetwork.xsd) [ro/4.0/RoadTransportNetwork.xsd](http://inspire.ec.europa.eu/schemas/tn-ro/4.0/RoadTransportNetwork.xsd) | | tn-w | | [http://inspire.ec.europa.eu/schemas/tn-](http://inspire.ec.europa.eu/schemas/tn-w/4.0/WaterTransportNetwork.xsd) [w/4.0/WaterTransportNetwork.xsd](http://inspire.ec.europa.eu/schemas/tn-w/4.0/WaterTransportNetwork.xsd) | | os | | [http://www.ordnancesurvey.co.uk/xml/schema/pr](http://www.ordnancesurvey.co.uk/xml/schema/product/1.0/OSProduct.xsd) [oduct/1.0/OSProduct.xsd](http://www.ordnancesurvey.co.uk/xml/schema/product/1.0/OSProduct.xsd) | | network | [http://namespaces.os.uk/mastermap/generalN](http://namespaces.os.uk/mastermap/generalNetwork/2.0) [etwork/2.0](http://namespaces.os.uk/mastermap/generalNetwork/2.0) | [https://www.ordnancesurvey.co.uk/xml/schema/n](https://www.ordnancesurvey.co.uk/xml/schema/network/2.0/generalNetwork.xsd) [etwork/2.0/generalNetwork.xsd](https://www.ordnancesurvey.co.uk/xml/schema/network/2.0/generalNetwork.xsd) | | highway | [http://namespaces.os.uk/mastermap/highway](http://namespaces.os.uk/mastermap/highwayNetwork/2.0) [Network/2.0](http://namespaces.os.uk/mastermap/highwayNetwork/2.0) | [http://www.os.uk/xml/schema/highwaysnetwork/](http://www.os.uk/xml/schema/highwaysnetwork/2.0/LinearHighwayNetwork.xsd) [2.0/LinearHighwayNetwork.xsd](http://www.os.uk/xml/schema/highwaysnetwork/2.0/LinearHighwayNetwork.xsd) | | ram | [http://namespaces.os.uk/mastermap/routingA](http://namespaces.os.uk/mastermap/routingAndAssetManagement/2.0) [ndAssetManagement/2.](http://namespaces.os.uk/mastermap/routingAndAssetManagement/2.0)1 |

2.1/RoutingAndAssetManagement.xsd

| | hwtn | [http://namespaces.os.uk/mastermap/highways](http://namespaces.os.uk/mastermap/highwaysWaterTransportNetwork/1.0) [WaterTransportNetwork/1.0](http://namespaces.os.uk/mastermap/highwaysWaterTransportNetwork/1.0) | [http://www.os.uk/xml/schema/highwaysnetwork/](http://www.os.uk/xml/schema/highwaysnetwork/v1/HighwaysWaterTransportNetwork.xsd) [v1/HighwaysWaterTransportNetwork.xsd](http://www.os.uk/xml/schema/highwaysnetwork/v1/HighwaysWaterTransportNetwork.xsd) | | dedication | [http://namespaces.os.uk/mastermap/highway](http://namespaces.os.uk/mastermap/highwayDedication/1.0) [Dedication/1.0](http://namespaces.os.uk/mastermap/highwayDedication/1.0) | [https://www.ordnancesurvey.co.uk/xml/schema/h](https://www.ordnancesurvey.co.uk/xml/schema/highwaysnetwork/1.0/HighwayDedication.xsd) [ighwaysnetwork/1.0/HighwayDedication.xsd](https://www.ordnancesurvey.co.uk/xml/schema/highwaysnetwork/1.0/HighwayDedication.xsd) |