🆕Tidal Boundary Continuous High
This page details upcoming data that will be provided for the Tidal Boundary Continuous High Feature Type in the OS NGD from the end of September 2025 to give you early insight. Data schema version 1.0 for this feature type is currently not available through the live access services. The information on this page is as accurate as possible, but is subject to change before launch.
The alignment of the limit of tidal water at Mean High Water (or Mean High Water Springs in Scotland), formed by merging individual Tidal Boundary features.
Temporal filtering
The earliest date on which you can request a one-off snapshot of a date in the past for data in this feature type is 25 September 2025; any data temporally filtered earlier than the specified earliest date noted for the data schema version may contain data inconsistencies.
What is temporal filtering?
Temporal filtering allows you to order a one-off snapshot of data from the OS NGD from a current or past date. It is an optional step when you create a new data package in OS Select+Build (the OS NGD download service). More information about temporal filtering on OS NGD feature types is available from the Getting started with temporal filtering guide.
Feature type attributes
The following sub-sections provide details about the attributes included with this feature type, their data types in the different output formats, and other important metadata about them.
Loading OS NGD CSV files into databases
Comma-separated values (CSV) file format is universally supported for easy ingestion into all major database products. Before loading OS NGD data contained in CSV files into a database, it is necessary to create relevant tables. Data definition language (DDL) statements for PostgreSQL, SQL Server and Oracle can be accessed in our OS NGD Resources GitHub repository.
For instructions on loading CSV files, see the Getting Started with CSV guide.
osid
Primary identifier for the feature. The OSID is a Globally Unique Identifier (GUID) and requires no centralised authority to ensure uniqueness. Note that the same OSID can occur in more than one feature type when a single feature is represented multiple times in the OS NGD.
Data Types: String (GeoJSON), String (GPKG), String (CSV)
Nullable: false
Max Length: 36
OS NGD API – Features Filterable: Yes
OS Select+Build Filterable: No
Data Schema Version: 1.0
versiondate
Date when the version was last updated.
Data Types: String (GeoJSON), Date (GPKG), Date (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
versionavailablefromdate
The date this version of the feature became the latest version.
Data Types: String (GeoJSON), DateTime (GPKG), DateTime (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
versionavailabletodate
The date this version of the feature was superseded by an update or ceased to exist.
Data Types: String (GeoJSON), DateTime (GPKG), DateTime (CSV)
Nullable: true
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
firstdigitalcapturedate
Represents the date on which a feature was first digitised by Ordnance Survey.
Data Types: String (GeoJSON), DateTime (GPKG), DateTime (CSV)
Nullable: true
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
changetype
The type of change that generated a new version of the feature.
Data Types: String (GeoJSON), String (GPKG), String (CSV)
Nullable: false
Code List Name: changetypevalue
Max Length: 50
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
geometry
Geometry for the feature.
Data Types: Geometry (GeoJSON), Geometry (GPKG), WKT (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
Geometry Type: LineString
geometry_length_m
The measured length of the geometry in metres.
Data Types: Integer (GeoJSON), Integer (GPKG), Integer (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
geometry_evidencedate
The date on which the latest evidence was gathered to make an update if required. For example, the date of collection by a surveyor or third party information received.
Data Types: String (GeoJSON), Date (GPKG), Date (CSV)
Nullable: true
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
geometry_updatedate
Date when the attribute was last updated.
Data Types: String (GeoJSON), Date (GPKG), Date (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
theme
The OS NGD theme to which this feature belongs.
Data Types: String (GeoJSON), String (GPKG), String (CSV)
Nullable: false
Code List Name: themevalue
Max Length: 40
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
description
A single descriptive value intended for a quick understanding of what the feature represents.
Data Types: String (GeoJSON), String (GPKG), String (CSV)
Nullable: false
Code List Name: tidalboundarycontinuoushighdescriptionvalue
Max Length: 25
OS NGD API – Features Filterable: Yes
OS Select+Build Filterable: Yes
Data Schema Version: 1.0
description_evidencedate
The date on which the latest evidence was gathered to make an update if required. For example, the date of collection by a surveyor or third party information received.
Data Types: String (GeoJSON), Date (GPKG), Date (CSV)
Nullable: true
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
description_updatedate
Date when the attribute was last updated.
Data Types: String (GeoJSON), Date (GPKG), Date (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
iscoincidentwithlow
Indication that the feature is both mean high water and mean low water and also exists in the Tidal Boundary Continuous Low dataset.
Data Types: Boolean (GeoJSON), Integer (GPKG), String (CSV)
Nullable: false
OS NGD API – Features Filterable: No
OS Select+Build Filterable: No
Data Schema Version: 1.0
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