Add new variability type and update comments

Signed-off-by: Thomas Sedlmayer <tsedlmayer@pmsfit.de>

Author: thomassedlmayer

osi_trafficsign.proto

@@ -9571,23 +9571,35 @@ message TrafficSign
         //
         VARIABILITY_OTHER = 1;
 
-        // Sign that can change neither semantically nor positionally, e.g.
-        // fixed immutable traffic sign.
+        // Sign that can change neither semantically nor positionally, e.g. a
+        // fixed, immutable, non-temporary traffic sign.
         //
         VARIABILITY_FIXED = 2;
 
-        // Sign that can change semantically and positionally.
+        // Sign that can change semantically and/or positionally, i.e. it is
+        // left unspecified in which way the sign may change.
+        //
+        // \note This value represents a legacy definition. If possible, please
+        // use the more specific values below to indicate the exact nature of
+        // variability.
         //
         VARIABILITY_VARIABLE = 3;
 
-        // Sign that can change positionally but not semantically, e.g.
-        // temporary immutable traffic sign at construction site.
+        // Sign that can change positionally but not semantically, e.g. a
+        // temporary, immutable traffic sign at construction site.
+        //
+        VARIABILITY_MOVABLE = 4;
+
+        // Sign that can change semantically but not positionally, e.g. a
+        // digital traffic sign on traffic sign gantry, or an analog prism
+        // sign.
         //
-        VARIABILITY_VARIABLE_MOVABLE = 4;
+        VARIABILITY_MUTABLE = 5;
 
-        // Sign that can change semantically but not positionally, e.g. digital
-        // traffic sign on traffic sign gantry or analog prism signs.
+        // Sign that can change both semantically and positionally, e.g. a
+        // temporary, digital traffic sign at a construction site, or a digital
+        // traffic sign attached to a road works vehicle.
         //
-        VARIABILITY_VARIABLE_MUTABLE = 5;
+        VARIABILITY_MOVABLE_AND_MUTABLE = 6;
     }
 }