Product glossary

Glossary term	Definition
Address, addressed premises	A permanent or non-permanent location with an address being a potential delivery point for Royal Mail. Examples of addressed premises are a house, a flat within a block of flats, a caravan site, a bollard to which several houseboats may be moored or an organisation occupying the whole or part of a building.
Attribute	Any item of information packaged in an OS MasterMap feature. The TOID and the geometry of the feature are both attributes of the feature. In GML and XML documents and specifications, this term is used in a different way. This usage is noted in the OS MasterMap specification as appropriate.
Customer	An organisation or individual that makes use of Ordnance Survey’s data supply facilities. This includes both direct sales customers of Ordnance Survey and Ordnance Survey Mapping and Data Centres, as well as customers of Licensed Partners. It does not include anyone, or any organisation, that has access to Ordnance Survey material without charge.
Dataset	An identifiable set of data that shares common characteristics and that is managed as a subset of the data within a database.
Digital National Framework (DNF)	A nationally consistent geographic referencing framework for Great Britain, comprising the National Grid and the National Geographic Database, that defines each geographic feature as it exists in the real world with a maintained, unique reference allocated to each feature. The DNF is not a product; it is the framework on which our future products will be based.
Feature	An abstraction of a real-world object. It is not the real-world object itself. The OS MasterMap product is composed of discrete vector features, each of which has a feature type, geometry, and various feature attributes.
GML	Geography Markup Language. An XML encoding for the transport and storage of geographic information, including both the geometry and attributes of geographic features.
INSPIRE	The INSPIRE directive aims to create a European Union (EU) spatial data infrastructure. This will enable the sharing of environmental spatial information among public sector organisations and better facilitate public access to spatial information across Europe.
Layer	A layer is a group of related OS MasterMap themes. A layer may consist of one or more themes. For example, the Sites Layer is currently composed of seven themes, whereas the Topography Layer contains seven themes.
Life cycle	The series of events that occur in the life of a real-world object or the OS MasterMap feature(s) that represents it. This will always include those events that result in creation and deletion and may also include events that result in amendments or change.
National Grid	A unique referencing system that can be applied to all Ordnance Survey maps of Great Britain at all scales. It provides an unambiguous spatial reference for any place or entity in Great Britain.
Obscured level	Where more than one level of detail exists, all detail that meets the specification for capture positioned below cartographic surface level and either at or above ground surface level is captured as obscured detail. For example, detail under bridges is obscured whilst the bridge itself is at normal cartographic level.
Order	A request from a customer for the supply of data. The scope of an order may be constrained by an agreement for a period licence service.
Point	A pair of coordinates.
Point feature	A feature representing a real-world object. The geometry of a point feature is a single point (a pair of coordinates) with optional size and orientation.
Polygon	Polygons are representations of areas. A polygon is defined as a closed line or perimeter that completely encloses a contiguous space and is made up of one or more lines.
Polygon feature	A polygonised representation of a real-world object. A polygon feature may be used to represent a building, field, lake, functional site extent and so on.
Positional accuracy	The accuracy of the feature geometry relative to the coordinate spatial reference system.
Real-world object	The real thing represented by a feature; for instance, a building, a section of fence, the boundary of a wood or a sharp change of gradient. For comparison, an example of a non-real-world object would be the line of an administrative boundary.
Spatial reference system	The term used in GML (and hence in OS MasterMap specifications) for the definition that allows each spatial position to be stated as a tuple. The only spatial reference system currently used in OS MasterMap is the British National Grid.
Supply format	The file format in which the data is supplied to the customer.
Theme	A collection of features that form some logical set, for example, buildings, water, land. In the OS MasterMap context, themes are a collection of features that are either similar in nature or are related to specific usage. A single feature may be in one or more themes. They are designed to allow the easy selection of features. They do not form part of the classification of the feature. The theme exists purely to facilitate customer data selection.
TOID	An identifier that uniquely identifies every feature.
Version date	The date the version of the feature was created by Ordnance Survey within its master database of OS MasterMap.
Version number	A version number will identify that a feature has been altered. Version numbers will be allocated sequentially, with version 1 representing the creation of the feature.
XML	eXtensible Markup Language. A flexible way to create common information formats and share both the format and the data on the Internet, Intranets and elsewhere. XML is extensible because, unlike HTML, the markup tags are unlimited and self- defining. XML is a simpler and easier to use subset of the Standard Generalised Markup Language (SGML), the standard for how to create a document structure.