The API version you use controls the behaviour of the API. The first time you register to use Fullscript's API you will be assigned the latest version.
The current version for Fullscript's API is Version 2. If we ever make a breaking change to the API we will release a new dated patch_version with the new behaviour. We do this to avoid breaking any of your code. It's up to you to upgrade if / when you want to.
The latest patch_version is 2020-02-14.
The Fullscript API considers the following changes to be backwards compatible (ie. non-breaking changes).