Is it possible to update a user or device's externally owned value using the xMatters API?
All versions of xMatters
Yes, as an externally owned value is a property of a user or device, by modifying a user or device in the system, you can update externally owned values using a curl command.
curl -H "Content-Type: application/json" --user username -X POST -d
Note: You will need to have the user's UUID to be able to call them up and modify as needed. The values for externallyOwned are case sensitive, so use true or false only.
To learn about about modifying users through the xMatters API, see Modify a person.