diff --git a/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-stations-1.json b/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-stations-1.json
index 6aaecb1553647660ba1cdae98a680ec197abd49f..257835dd7ae38e1d70d69685d2e47f568463e745 100644
--- a/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-stations-1.json
+++ b/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-stations-1.json
@@ -68,7 +68,6 @@
         ]
       },
     "station_list":{
-      "title":"fixed station list",
       "default":[
         "CS001"
       ],
@@ -78,56 +77,55 @@
       "items":{
         "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/stations/1#/definitions/station"
       },
-      "minItems":1,
+      "minItems":0,
       "uniqueItems":true
     },
-    "station_set":{
-      "title":"dynamic station set",
+    "station_group":{
+      "title":"Station group",
       "type":"object",
       "default":{},
       "additionalProperties":false,
       "properties":{
-        "group":{
+        "name":{
+          "type":"string",
+          "title":"Group name",
+          "description":"Which group to select from",
+          "default":"ALL"
+        },
+        "stations":{
           "type":"string",
-          "title":"StationGroup",
-          "description":"Which (group of) station(s) to select from",
-          "default":"ALL",
-          "enum":[
-            "ALL",
-            "SUPERTERP",
-            "CORE",
-            "REMOTE",
-            "DUTCH",
-            "INTERNATIONAL"
-          ]
+          "title":"Stations",
+          "description":"Which stations belong to this group",
+          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/stations/1#/definitions/station_list"
         },
-        "min_stations":{
+        "max_missing":{
           "type":"integer",
-          "title":"Minimum nr of stations",
-          "description":"Number of stations to use within group/station",
-          "default":1,
+          "title":"Maximum nr of stations to omit",
+          "description":"Number of stations that can be omitted within group",
+          "default":0,
           "minimum":0
         }
       },
       "required":[
-        "group",
-        "min_stations"
+        "name",
+        "max_missing"
       ]
     },
     "stations": {
-      "title":"stations",
-      "description":"Use either the fixed station list, or one of the dynamic station sets.",
-      "oneOf": [ {
-          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/stations/1#/definitions/station_list"
-        },
-        {
-          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/stations/1#/definitions/station_set"
-        }
-      ],
-      "default": {
+      "title":"Stations",
+      "type":"array",
+      "additionalItems":false,
+      "additionalProperties":false,
+      "description": "Station selection constraints",
+      "items":{
+        "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/stations/1#/definitions/station_group"
+      },
+      "minItems":1,
+      "default": [ {
         "group": "ALL",
-        "min_stations": 1
-      }
+	"stations": [],
+        "max_missing": 0
+      } ]
     },
     "antenna_set":{
       "type":"string",
@@ -163,4 +161,4 @@
       ]
     }
   }
-}
\ No newline at end of file
+}