REST API Endpoint SetLevel

I have a zigbee dimmer switch. The endpoint has setLevel option, but looking at the community forum, I cannot figure out how to set value of the dimmer. Is this reserved for a future date?

https://graph.api.smartthings.com/api/smartapps/installations/XXXX-XX-XXX-XXXX/switches/XX-XXX-XXX/setLevel?access_token=XX-XXX-XXXX