diff --git a/openstack/blockstorage/extensions/tenantattr/results.go b/openstack/blockstorage/extensions/tenantattr/results.go
index 5e9ef23..6e1cd15 100644
--- a/openstack/blockstorage/extensions/tenantattr/results.go
+++ b/openstack/blockstorage/extensions/tenantattr/results.go
@@ -1,5 +1,7 @@
 package tenantattr
 
+// An extension to the base Volume object
 type VolumeExt struct {
+	// TenantID is the id of the project that owns the volume.
 	TenantID string `json:"os-vol-tenant-attr:tenant_id"`
 }