This section explains the representation of features in Boundary-Line and describes various definitions and exceptions.
Administrative area
This term is used by Ordnance Survey to refer to all public administrative areas. For the Boundary-Line dataset, the following are included under this term:
In England
County
Unitary authority
Metropolitan district
District
Civil parish (Note: Depicted if appropriate notification has been received. Not all parishes have councils.)
English region
Parliamentary (Westminster) constituency
Electoral division (of county or unitary authority)
Ward (of district, metropolitan district, London borough, unitary authority)
London borough (including the county of the City of London)
Greater London Authority
Greater London Authority Assembly constituency
In Wales
Unitary authority
Community (Note: Depicted if appropriate notification has been received.)
Parliamentary (Westminster) constituency
Electoral division (of unitary authority)
Welsh Parliament constituency
Welsh Parliament electoral region
In Scotland
Unitary authority
Parliamentary (Westminster) constituency
Ward (of unitary authority)
Scottish Parliament constituency
Scottish Parliament electoral region
Area values
Area values exist for every polygon in Boundary-Line; area values are quoted to the current Department for Communities and Local Government (DCLG) specification of 0.001 hectare. The value is subject to the inherited accuracies of the generalised 1:10 000 scale published mapping used as the source for Boundary-Line.
Boundary
A boundary is the limit of a pre-set and established area whose limit is determined by one or more lines. For example, in Boundary-Line, an administrative unit boundary is represented by a county area boundary.
Ceremonial counties
A ceremonial county is an area that has an appointed Lord Lieutenant and High Sheriff. Ceremonial counties are not explicitly represented in Boundary-Line.
Complex polygons
Complex polygons are polygons that wholly enclose other polygons. They only occur when an administrative unit wholly encloses one or more others at the same level, for example, a rural district surrounding an urban district.
Detached parts
The description ‘Detached (Det)’, only applies to portions of local government or parliamentary constituency areas which are separated from the main area, being completely surrounded by other local government or parliamentary constituency areas and not connected by direct access on the ground.
The description will not be applied to islands or parts of islands in the sea. Detached parts have the same GSS code (where applicable) as the main area.
Divorcement
Part of a boundary separated from another, originally on the same alignment. Divorcements are created by the revision of one boundary and not the other.
The figure above shows a boundary divorcement. The unitary boundary between Vale of Glamorgan and Cardiff has been realigned, whilst the parliamentary (Westminster) constituency boundary has remained in its original position. It is likely that the parliamentary (Westminster) constituency boundary will also be realigned at some time in the future.
Effective date
These are the dates on which an Act, Order or Statutory Instruments are ‘effective’. They may or may not be the same as the operative date or the appointed day or days. The term is particularly applied to parliamentary (Westminster) constituency changes that are effective at the date of the next general election after the operation of the order making change. This is the ‘effective’ date, that is, the date of the proclamation dissolving an existing Parliament and calling a new Parliament.
Exception areas
The following are specific exceptions to the normal rules:
Greater London and the metropolitan counties:
Greater London covers the area of the 32 London boroughs plus the City and county of the City of London.
Greater London is no longer a county. The Greater London Authority, which has no authority over the autonomous London boroughs, is held as one named file with all the sub-levels of boundary within it.
The London boroughs and the City and county of the City of London have been classified as London boroughs.
The metropolitan districts within the former metropolitan counties (disbanded in 1985) are classified as metropolitan districts:
Greater Manchester
Merseyside
South Yorkshire
West Yorkshire
Tyne and Wear
West Midlands
Government Office Regions
Government Office Regions (GORs) in England are not represented as specific boundary features in Boundary-Line; however, the boundaries that are used to define the GORs are represented as English Regions. A full list of the counties and unitary authorities that represent each English Region which the GORs are based on can be found in the Boundary-Line release note.
Honorary titles
Honorary titles granted to local government areas such as city and town are not included in Boundary-Line.
Boroughs in England have been identified, as from the October 2006 release, with (B) in the file name and
(B) in the Name attribute, for example:
The borough (B) will only be depicted on unitary authorities, district and metropolitan districts. This addition is to purely denote which boundaries have borough status in England without creating polygons or altering the specification in any way.
National boundaries
The boundaries between England and Wales and England and Scotland are represented by the boundaries between countries in the supplementary Country layer. These are maintained boundary extents based off local authority boundaries.
Government Statistical Service codes
Government Statistical Service (GSS) codes are a unique system of referencing for administrative units.
All types of units are coded in Boundary-Line except for Greater London Authority, county electoral divisions and non-civil-parish areas. The County ED code for Greater London Authority is set at 999999999. The code is blank when the administrative unit does not have a code, for example, non-civil- parish areas.
The codes are allocated by the Office for National Statistics (ONS) for England and Wales and by the General Register Office for Scotland (GROS) for Scottish areas.
Operative dates
This is a calendar date, given in an Order, Act or Statutory Instrument, on which the specified boundary changes will come into operation. Dates given may be up to four years after the publication of the Order, Act or Statutory Instrument and may apply to any type of boundary other than parliamentary or European regions.
Order, Act or Statutory Instrument
The represented boundaries and administrative unit names are defined and modified by Orders, Acts and Statutory Instruments (SIs). A document signed by the relevant Secretary of State or a local authority letter describing and giving legal authority for boundary changes.
Superseded date
This is the last date on which a boundary was current. Where an effective date applies, the superseded date will be the day before the next dissolution of Parliament.
Boundaries are no longer shown in Boundary-Line if they have been superseded at the time of the annual snapshot of boundaries that each release of Boundary-Line represents.
Survey change
When changes occur to tidelines, rivers or streams caused by natural and gradual forces, any boundaries that are linked to these altered features will move with them. When the movement of a boundary, MHW or EOR alignment in Boundary-Line reflects such changes, this will be noted in the update notes that accompany each release of Boundary-Line.
Unannexed areas
This is an area within the realm that is not included in all the relevant administrative units. The area will remain unannexed until further legislation changes its situation and the polygon represents a hole in that level of administration.
Unitary authorities
Unitary authorities and counties effectively create a contiguous layer of administrative units throughout the whole of Great Britain. They represent single-tier administrations with responsibility for all areas of local government.
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