> For the complete documentation index, see [llms.txt](https://docs.os.uk/os-downloads/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.os.uk/os-downloads/products/transport-network-portfolio/os-mastermap-highways-network-routing-and-asset-management-information/os-mastermap-highways-network-routing-and-asset-management-information-technical-specification/advisory-information/feature-types/structure.md).
# Structure
These indicate the location of key structures related to the highway network. These may be:
* **Barriers**: Structures or equipment constructed to control, obstruct or prevent passage or access
* **Bridges and Tunnels**
* **Crossings and Signals**: Equipment such as traffic signals, and locations that control the flow of traffic
A Structure will reference back to the Roads product through a Node Reference, Link Reference or Point Reference.
Context diagram: Structure
## Structure attributes
A built feature with relation to the highway network.
### id
Unique identifier, for Structure this is a TOID.
* **Attribute name:** id
* **Type:** CharacterString
* **Size:** 20
* **Multiplicity:** \[1]
### identifier
Uniform Resource Identifier.
* **Attribute name:** identifier
* **Type:** CharacterString
* **Size:** 37
* **Multiplicity:** \[1]
### inspireId
External object identifier of the spatial object.
* **Attribute name:** inspireId
* **Type:** [Identifier](/os-downloads/products/transport-network-portfolio/os-mastermap-highways-network-routing-and-asset-management-information/os-mastermap-highways-network-routing-and-asset-management-information-technical-specification/data-types/identifier.md)
* **Multiplicity:** \[0..1]
### beginLifespanVersion
Date and time at which this version of the spatial object was inserted or changed in the spatial data set. Note: The time part is always set to zero.
* **Attribute name:** beginLifespanVersion
* **Type:** DateTime
* **Multiplicity:** \[1]
### networkRef
Spatial reference of the network-related property.
* **Attribute name:** networkRef
* **Type:** NetworkReference
* **Multiplicity:** \[1..\*]
### validFrom
The time when the transport property started to exist in the real world. Note: The time part is always set to zero.
* **Attribute name:** validFrom
* **Type:** DateTime
* **Multiplicity:** \[1]
### structure
Type of built feature.
* **Attribute name:** structure
* **Type:** [StructureTypeValue](/os-downloads/products/transport-network-portfolio/os-mastermap-highways-network-fundamentals/os-mastermap-highways-network-code-lists/structuretypevalue.md)
* **Size:** 39
* **Multiplicity:** \[1]
### description
Additional information describing the structure.
* **Attribute name:** description
* **Type:** CharacterString
* **Size:** 50
* **Multiplicity:** \[0..1]
### reasonForChange
The reason for a change made to a feature.
* **Attribute name:** reasonForChange
* **Type:** [ChangeValue](/os-downloads/products/transport-network-portfolio/os-mastermap-highways-network-fundamentals/os-mastermap-highways-network-code-lists/changevalue.md)
* **Size:** 32
* **Multiplicity:** \[1]
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.os.uk/os-downloads/products/transport-network-portfolio/os-mastermap-highways-network-routing-and-asset-management-information/os-mastermap-highways-network-routing-and-asset-management-information-technical-specification/advisory-information/feature-types/structure.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.