This operation lists all versions of an environment. You can modify a version until it's activated. Once you activate a version, you need to create a new one to edit its settings. An environment is a variant of an application or service in a given lifecycle stage, such as development, testing, or production. You create versions to experiment with rule settings and iterate without affecting other environments. Environment versions isolate different settings for your service until you explicitly promote them to production. Each environment version maintains its own change history of rule sets.