Smarter Drafter uses Path-based versioning to maintain backward compatibility when we release new changes to the API.
All endpoints begin with a v1 prefix, and where a resource defines more than one version available, this can be changed to access a different version.

Backward-compatible changes
Smarter Drafter considers the following changes to be backward-compatible:

Adding new optional parameters to an endpoint.
Adding new response properties to an endpoint's response.
Adding new Connect event types.

Backwards-compatible changes can be introduced to existing endpoint versions without prior warning, and your application is expected to handle them graciously.
Smarter Drafter considers the following changes not to be backward-compatible, resulting in a new endpoint version being released:

Removing an endpoint's request parameter or modifying its behaviour.
Removing a response property from an endpoint's response or modifying its type.
Introducing new validation rules to an endpoint's request parameters.
Changing an endpoint's HTTP response code.