OS MasterMap^® online service glossary

Tip: to search within this page, click on Ctrl and F.

About to expire (contract)

A contract which is within thirty days of the end of its licence period.

Account

Every OS MasterMap customer has an account.  This is more than just a financial account, but an overarching term for the agreements, orders, access rights and financial arrangements that a customer has with Ordnance Survey.

Active (estimate)

An estimate which has been created, but not converted to a contract and which is less than six months old.

Active (contract)

A contract which is still within its licence period.

Address Layer

Derived from the Royal Mail's Postcode Address File, this layer contains precise coordinates for each address in the country.This is a glossary of words and terms used in the OS MasterMap online service; that is, the Data Selector and the various automatic emails generated by it. It does not include words, terms and descriptions associated with OS MasterMap data itself; these are covered by a more comprehensive glossary in the OS MasterMap user guide.

Address Layer 2

Like ADDRESS-POINT® and Address Layer, Address Layer 2 is based on the Royal Mail® Postcode Address File (PAF®) and provides a spatial coordinate to a resolution of 0.1 m for each address.  OS MasterMap Address Layer 2 builds on the success of Ordnance Survey's current addressing products by offering significant enhancements such as Alternative geographic addresses, Classifications, Objects without a postal address, Multi-occupancies without postal addresses, Objects not yet built and a Cross reference function.

Change-only update (COU)

The ability to supply to a customer only those features that have been created or changed since a specified date. Change-only supply includes a list of the TOIDs of deleted features. In the OS MasterMap context, the selection of changed data will be by change-since date (that is, all change since 00:00 hours on the specified date). It is not possible to select change since your last update. Therefore the customer system must recognise repeatedly supplied features.

Change-since date

The date used when requesting change-only update that indicates the date since which change is required. This will result in the supply of all change in the database, since the beginning (that is, 00:00) of that day. To ensure there are no temporal gaps in your holdings, it is important that you enter the extraction date in the 'change since' window on the online service and not the availability date or the date that you last placed an order. Further information.

Chunking / chunks

The process of breaking up the area of order into manageable, physical units of supply (chunks, that is, files) for supply to the customer.

Contract

The agreement that a customer has for access to Ordnance Survey products and services. An OS MasterMap contract will be defined for each layer in terms of an area of interest, a list of themes (where appropriate), a time period, the number of terminals the data will be used on and a set of terms and conditions.

Converted (estimate)

An estimate that has been converted to a contract.

Currency date

Also known as the extraction date. This is the date that date that the data was last updated in the OS MasterMap database at Ordnance Survey. This is the date you must use when you place a COU order, to ensure there is not a gap in your data holdings. It is not not the availability date or the date that the order was placed. .  

On change-only update orders, instead of the 'currency date' the labels show 'COU from xx/xx/xx to xx/xx/xx'. The first is the date, input when the order was placed, from which changes to our OS MasterMap database are required; the second date is the date the database was last updated, ie the 'currency date'.

Estimate

A single price being offered to the OS MasterMap customer, as the cost of a proposed service definition agreement.

Expired (contract)

A contract that is no longer valid as it has passed the end of its license period.

Expired but renewable (contract)

A contract which, although it has passed the end of its licence period, can be renewed through the creation of a new estimate.

Expired but renewable (estimate)

An estimate older than thirty days that can be renewed, although the price will be recalculated.

Extraction date

The labels of CDs and DVDs containing OS MasterMap Imagery data have just one date, the extraction date. This is the date on which the imagery data is downloaded from our main database.

Feature Validation Data Set (FVDS)

CSV (comma separated value) text files which can be optionally supplied with an OS MasterMap order.  Using the FVDS data, a customer can check that their data holding is complete and correct.

FTP

File transfer protocol. A protocol that allows a user on one computer to transfer files to and from another computer over a TCP/IP network (for example, Internet).

GML

Geography Mark-up Language. An XML encoding for the transport and storage of geographic information, including both the geometry and attributes of geographic features.

Geographic chunking 

OS MasterMap data is supplied divided into a set of files (called chunks) so that each file is of a manageable size. This division can be made in two ways, Geographic or Non-geographic chunking, the customer being given the choice when ordering. With Geographic chunking the customer also selects the chunk size that the data is to be divided into (MGBS orders have preset chunk sizes). Geographic chunking results in the duplication of data along chunk joins, and hence orders have a larger data volume than if chunked non-geographically. However it does mean that a portion of the data can be loaded and used independent of the remainder of the order.

Great Britain (GB)

Great Britain is defined as the political entity which is made up of England, Scotland and Wales, including their offshore islands. It does not include the Isle of Man, the Channel Islands nor Northern Ireland, but includes the Isles of Scilly, and the Shetland and Orkney Islands.

Imagery Layer

A detailed aerial map created from high-quality orthorectified photography.

Import polygon

The process whereby a customer can import their own user defined polygon to create an estimate.

Independent polygon

OS MasterMap product feature geometry/topology, in which the data is simplified into area, point and line features with no relationship between them, and with their own explicit geometry. For example, in the independent polygon product the bounding line between two areas will be represented three times, each with their own description of the geometry. Once as a line feature, once as part of the bounding line of the first area feature, and once as part of the bounding line of the second area feature.

Integrated Transport Network® (ITN®) Layer

The ITN layer provides a detailed overview of the country's road network. Currently there are two themes available: The Roads Network (representing the roads in Great Britain) and Road Routing Information (RRI) (height and vehicle type restrictions, traffic calming, turn restrictions and one-way roads).

JPEG

Joint Photographic Experts Group. Image format.

Layer

A layer is a group of related OS MasterMap themes. A layer may consist of one or more themes. For instance, the Topography Layer is composed of nine themes, whereas the Address Layer contains only one theme.

Licence period

One, two or three year period that the customer is licensed to use OS MasterMap data for. See terms and conditions.

Locked (contract)

A contract that is currently being expanded or renewed. It is locked to prevent any further expansion or renewal estimates being created; but orders can still be placed against it.

Locked (estimate)

An estimate for an existing contract that has been superseded by an expansion estimate. The previous estimate becomes ‘locked' when the new one is created.

Locked out

Account status if the wrong username and/or password has been input ten times.

Managed GB Set (MGBS)

As demand for OS MasterMap data increased, customers requiring coverage of GB experienced longer delivery times for their data. To address this situation a service called Managed GB Sets has been introduced for customers with GB contracts, with the aim of ensuring that large orders are delivered in a reliably predictable and acceptably timely manner. See our planned schedule of MGBS updates.

Media created on

The bottom line of text on media labels of non-imagery orders, in small type, gives the 'Media created on' date. This is the date the CD/DVD was actually created at Ordnance Survey and shows a reference number of the robot that the media was created on. This enables us to identify it in case a problem is found with the media.

Media supply

The supply of data to a customer on physical media for OS MasterMap this will be either on CD or DVD.

MOWPA

Multi-occupancies without a postal address are based on the addresses in the Royal Mail’s new Multi-residence file. These contain residential premises that fall outside the Royal Mail’s definition of a 'delivery point', that is, mail is addressed to them but the postman can’t ordinarily access the letter box. That could mean flats within a house where the postman can only get to the house front door.

MrSID

A format for supplying imagery data.

National cover

Complete GB cover of an OS MasterMap layer.

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. Click here for further informaiton.

Non-bounding line flags

OS MasterMap Topographic Line features which do not form the boundary between Topographic area features carry an attribute indicationg that they are non-bounding lines.

Non-geographic chunking (NGC) 

OS MasterMap data is supplied divided into a set of files (called chunks) so that each file is of a manageable size. This division can be made in two ways, Geographic chunking or NGC, the customer being given the choice when ordering. With NGC the customer specifies the maximum data volume for each chunk. When the data in one file reaches this limit, a new file is started. This minimises the data volume of the order by removing the duplication found with Geographic chunking, but because features are divided into chunks randomly, all chunks should be loaded to ensure complete coverage of any area of the order.

Online supply

The supply of data to a customer using Internet technologies (eg via an FTP server).

Order

A request from a customer for the supply of data.

Order date

The order date is that on which the order was placed. It is not the date when the OS MasterMap database was last updated (the currency date) so should not be used when placing subsequent change-only update orders.

Orthorectified imagery

The Imagery Layer is orthorectified. An orthoimage is achieved through a rigorous mathematical modelling of the camera position/direction and the terrain surface at the moment of image exposure. A software process is then able to move each of the pixels in the image individually into its correct National Grid position. The process eliminates displacements due to image perspective and pointing direction (the aircraft is moving and rolls around all axes) and topographic relief and therefore results in an image having the same geometric properties as a map projection.

OWPA

Objects without a postal address are sourced from the OS MasterMap Topography Layer using relevant associated cartographic text. They are then given an Ordnance Survey generated geographic address.

Password

A unique combination of letters and/or numbers known only to a user or a restricted group of users. See password management guidance.

Point

A point is used to specify a single horizontal location by a coordinate pair in a given spatial reference system.

Polygon

See import polygon; independent polygon; pre-defined polygon; topological polygon; user defined polygon.

Positional accuracy

The accuracy of the feature geometry relative to the coordinate spatial reference system.

Pre-defined polygon

An existing geographic area (administrative areas; postcode area; M25 region) which can be used to order data for.

Price expired (estimate)

An estimate which is older than the validty period; thirty days for initial estimates; twenty-four hours for expansion estimates.

Real-world object

The real thing represented by a feature. For instance, a building, a section of fence, the boundary of a wood a sharp change of gradient.

Service level agreement (SLA)

An agreement between the Ordnance Survey and a group of customers to supply digital data.

Submitted (estimate)

An estimate that has been submitted for conversion to contract, but which has not completed the conversion process.

Supply format

The file format in which the data is supplied to the customer.

Terminals

Refers to PC/platform upon which the OS Mastermap data will be used. When creating an estimate you are required to specify the number of terminals the data will be used on.

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.

TIFF

Tagged Image File Format. Imagery format.

Tile

A self contained rectangular subset of digital data, used to subdivide that data into manageable units. OS MasterMap data has no tiles, however data is currently updated on a tile basis.

TOID®

A number that uniquely identifies every feature. No intelligence (for example, its coordinate position) about the feature can be derived from either the allocated number or the process by which it is allocated. The TOID will remain with the feature throughout its life and will not be reassigned to a new feature when the existing feature is deleted.

Topography Layer

A large-scale digital database of the detailed surface features on the landscape, covering some 400 million man-made and natural features, from fields to pillar boxes, each with its own unique identifier (TOID). It is broken down into nine themes to make it easier to access the data: roads, tracks and paths; land; buildings; water; rail; height; heritage; structures; and administrative boundaries.

Un-priced (estimate)

An estimate created to expand a contract that previously had less that nine Topo themes. Such an estimate would require you to contact the Customer Services team to confirm the price.

User defined polygon

Area of customer interest created using the freehand tools available during the estimating process.

Username

Eight character name beginning with ‘x' which in combination with a password, allows you access to the OS MasterMap online system.