Many tools support more than one root folder per workspace. Examples for this are VS Code's multi-root support, Atom's project folder support or Sublime's project support. If a client workspace consists of multiple roots then a server typically needs to know about this. The protocol up to know assumes one root folder which is announce to the server by the rootUri property of the InitializeParams. A protocol extension is proposed to add first class workspace folder support. A markdown documentation is here and a reference implementation for the client and server