# Data Structures
### ESR
ESR Data Structure
- refnum (string) - this is made up of a route specific prefix, a three digit incremental counter, plus the two digit year
- speed (object) - "Freight Speed / Passenger Speed" - single number if both are same, units and unrestricted line speed
- route (object) - all properties of the route- du (object) - responsible Delivery Unit
- elr (object) - ELR of track segment impacted e.g. LTN1
- lor (object) - LOR properties
- location (string) - description of where the restriction is applied, should be "At X" or "Between X and Y"
- reason (object) - describes reason the ESR is imposed
- withdrawn (bool) - 0 = active, 1 = withdrawn
- whenimposed (string) - W3C format date time string, updated during amendment
- etc (null|string) - if set this is a W3C format date time string
- whenwithdrawn (null|string) - if withdrawn === 1, W3C format date time string
- lines (array) - object for each "line". A "line" is the combination of ELR + TrackID
- elr (object) - as above
- trackId (int) - e.g. 1100 = Up Main
- direction (string) - "Up Direction" | "Down Direction" (yuk)
- linedescription (string) - can be driven by trackId or overridden by Controller
- boards (array)
- type (string) - short name (no spaces)
- description (string) - long name
- elrId (int) - copied from line
- trackId (int) - copied from line
- miles (int) -
- chains (int) - 0 >= X < 80
- serialNumber (string) - not currently used
- marker (GeoJSON)
- references (object)
- updated\_at - time of last database change
Example Response
```json
{
"id": 5,
"refnum": "AICC 001.26",
"speed": {
"value": "40",
"unit": "mph",
"linespeed": "120"
},
"route": {
"routecode": "EA",
"routename": "Anglia",
"shortname": "AICC",
},
"du": {
"name": "Ipswich",
"routeId": 2,
},
"elr": {
"elrcode": "LTN1",
"elrdescription": "LIVERPOOL STREET - TROWSE LOWER JN",
},
"lor": {
"lorcode": "EA1011",
"lordescription": "SEVEN KINGS TO IPSWICH",
},
"location": "At Colchester South Jn",
"reason": {
"reason": "Structural - Station",
},
"lines": [
{
"elr": {
"elrId": 668,
"elrcode": "LTN1",
"elrdescription": "LIVERPOOL STREET - TROWSE LOWER JN",
"active": true
},
"trackId": 1100,
"routeheader": "Primary Line",
"direction": "Up Direction",
"linedescription": "Up Main",
"newStyleBoards": true,
"boards": [
{
"type": "commencement",
"description": "Speed Indicator (Commencement)",
"elrId": 668,
"trackId": 1100,
"miles": 50,
"chains": 75,
"serialNumber": null,
"marker": {
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
0.876876605,
51.90208042
]
},
"properties": {
"type": "commencement",
"description": "Speed Indicator (Commencement)",
"elrId": 668,
"trackId": 1100,
"miles": 50,
"chains": 75,
"serialNumber": null
}
}
},
{
"type": "termination",
"description": "Termination Indicator",
"elrId": 668,
"trackId": 1100,
"miles": 49,
"chains": 75,
"serialNumber": null,
"marker": {
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [
0.85427535,
51.89894058
]
},
"properties": {
"type": "termination",
"description": "Termination Indicator",
"elrId": 668,
"trackId": 1100,
"miles": 49,
"chains": 75,
"serialNumber": null
}
}
}
]
}
],
"whenimposed": "2026-03-18 11:42:06",
"etr": null,
"withdrawn": false,
"whenwithdrawn": null,
"references": {
"fmsnumber": "123",
"ccilnumber": "23645657",
"tsrreference": "",
"tdanumber": "",
"wo": "",
"rdms": "",
"trustcode": "",
"owner": ""
},
"updated_at": "2026-03-18 11:42:06"
}
```