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6.2.2 • Public • Published


Javascript Cursor-On-Target Library

Lightweight JavaScript library for parsing and manipulating TAK related messages, primarily Cursor-on-Target (COT)


node-tak converts between TAK message protocols and a Javascript object/JSON format. It also can bidirectionally convert CoT messages into a GeoJSON format



To install node-cot with npm run

npm install @tak-ps/node-cot

CoT Spec

The CoT spec appears to be very informally developed by a rough internal concensus by large TAK Clients within the TPC (TAK Product Center). The following is a current understanding of the spec primarily developed through reverse engineering TAK clients

<event version uid type how time start stale/>

Event Attributes

Name Description Example
version CoT Version, currently 2.0 version="2.0"
uid Globally unique name for this information on this event uid="any-unique-string-123"
type Hierarchically organized hint about event type `type="a-f-G-E"'
how Gives a hint about how the coordinates were generated how=""
time The time at which the event was generated time="2023-07-18T15:25:09.00Z"
start The time at which the event starts or is relevant start="2023-07-18T15:25:09.00Z"
stale The time at which the event ends or is not relevant stale="2023-07-18T15:25:09.00Z"

CoT GeoJSON Spec

One of the primary use-cases of this library is to make serialization and deserialiation from more commmon geospatial formats a breeze. This section will walk through CoT options that are exposed via the from_geojson() function.

Supported Geometries

  • All Input Geometries must be a GeoJSON Feature type
  • Point, Polygon, and LineString are all supported
  • Multi Geometries are not supported and must be cast to their non-multi type before being passed to the library
  • Centroids are calulated using a PointOnSurface algorithm

Supported Properties

The following are the most important/relevant properties

Property Description
.id Used as the CoT uid - If omitted a UUID is generated
.properties.type CoT type - note this will be overridden if geometry is not a Point
.properties.how CoT how
.properties.time Time at which CoT was created
.properties.start Time at which CoT is relevant
.properties.stale Time at which CoT expires
.properties.callsign Displayed callsign (basically the name of the feature)
.properties.speed Speed in m/s of the object
.properties.course Course in degrees from north of the object
.properties.remarks Human readable remarks field

Styles can also be applied to features using the following

Property Description
.properties.stroke Polygon/LineString
.properties.stroke-opacity Polygon/LineString: Int from 0-256
.properties.stroke-width Polygon/LineString
.properties.stroke-style Polygon/LineString
.properties.stroke-style Polygon/LineString
.properties.fill Polygon
.properties.fill-opacity Polygon: Int from 0-256

These are less common properties that can be used:

Property Description
.properties.icon String: Custom Icon Path (string)
.properties.archived Boolean: TAK Clients will ignore the stale value and retain the feature

Usage Examples

Basic Usage

import CoT from '@tak-ps/node-cot';

const message = '<event version="2.0" uid="ANDROID-deadbeef" type="a-f-G-U-C" how="m-g" time="2021-02-27T20:32:24.771Z" start="2021-02-27T20:32:24.771Z" stale="2021-02-27T20:38:39.771Z"><point lat="1.234567" lon="-3.141592" hae="-25.7" ce="9.9" le="9999999.0"/><detail><takv os="29" version=" (deadbeef).1234567890-CIV" device="Some Android Device" platform="ATAK-CIV"/><contact xmppUsername="xmpp@host.com" endpoint="*:-1:stcp" callsign="JENNY"/><uid Droid="JENNY"/><precisionlocation altsrc="GPS" geopointsrc="GPS"/><__group role="Team Member" name="Cyan"/><status battery="78"/><track course="80.24833892285461" speed="0.0"/></detail></event>'

const cot = new CoT(message);

// Export Formats
cot.to_geojson(); // Output GeoJSON Representation
cot.to_xml(); // Output String XML Representation

cot.raw; // JSON XML Representation

Known Special CoT Types

The following list is a very incomplete list of "special" CoT types and behaviors

CoT Type Notes
u-d-f LineString or Polygon
u-d-r 4 Cornered Rectangle
b-a-o-tbl 911 Alert
b-a-o-can Cancel
b-a-g GeoFenceBreach
b-a-o-pan RingTheBell
b-a-o-opn TroopsInContact
b-t-f Chat
b-t-f-d Chat delivery receipt
b-t-f-r Chat read receipt
b-t-f-p Chat pending receipt
b-t-f-s Chat delivery failure
t-x-m-c-l Mission Change Notification

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