             }
 
         }
-        if let ol = type.properties[Keys.Overlays.rawValue] {
+        if let ol = type.properties[Key.Overlays.rawValue] {
             guard let overlays = ol.map else {
                 fatalError("Non-map overlay \(ol)")
             }

        case Tasks = "tasks"
        case Overlays = "overlays"
        case UseOverlays = "use-overlays"
    }
    
    // The required properties.

        var remotePackages: [Package] = []

        //load remote packages
        if let imports_nv = type.properties[Key.ImportPackages.rawValue] {
            guard let imports = imports_nv.vector else {
                throw PackageError.NonVectorImport
            }
