# API Version Description and Usage Instructions

EVS APIs provide multiple versions. For the APIs offering same functions, you are recommended to use the v2 APIs.

The current default microversion of v3 APIs is 3.0, and the maximum version is 3.50. You can specify the version number by adding OpenStack-API-Version:volume Version number to the request header. For example, add OpenStack-API-Version:volume 3.50.

v3 APIs are not recommended, especially non-OpenStack v3 APIs, which will be changed in the future. Therefore, v2 APIs are strongly recommended.