Microsoft SQL Server User CAL 2017 Volume licence
Microsoft SQL Server User CAL 2017 is a user-based access license for Microsoft SQL Server.
Contrary to device CALs (device licenses), Microsoft SQL Server User CAL 2017 provides an user with access to SQL Server.
Microsoft SQL User CAL 2017 is downgradable. For example, you can run it in combination with Microsoft SQL Server 2016.