diff --git a/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-datetime-1.json b/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-datetime-1.json
new file mode 100644
index 0000000000000000000000000000000000000000..d12982a89ed3b79fc306a4a26c2c667f60662e6a
--- /dev/null
+++ b/SAS/TMSS/src/tmss/tmssapp/schemas/common_schema_template-datetime-1.json
@@ -0,0 +1,33 @@
+{
+  "$id": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1#",
+  "$schema": "http://json-schema.org/draft-06/schema#",
+  "title": "datetime",
+  "description": "This schema defines datetime objects like timestamp and timewindow.",
+  "version": 1,
+  "type": "object",
+  "definitions": {
+    "timestamp": {
+      "description": "A timestamp defined in UTC",
+      "type": "string",
+      "pattern": "\\d{4}-[01]\\d-[0-3]\\dT[0-2]\\d:[0-5]\\d:[0-5]\\d(\\.\\d+)?Z?",
+      "format": "date-time"
+    },
+    "timewindow": {
+      "type": "object",
+      "description": "A timewindow interval: [from, to)",
+      "properties": {
+        "from": {
+          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timestamp"
+        },
+        "to": {
+          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timestamp"
+        }
+      },
+      "additionalProperties": false,
+      "required": [
+        "from",
+        "to"
+      ]
+    }
+  }
+}
\ No newline at end of file
diff --git a/SAS/TMSS/src/tmss/tmssapp/schemas/scheduling_constraints_template-constraints-1.json b/SAS/TMSS/src/tmss/tmssapp/schemas/scheduling_constraints_template-constraints-1.json
index dbbef582894ffcf0852c4235695124ce96afe5a3..ca8a3f6754ecdb8aee96c52f31ea14a20b4229aa 100644
--- a/SAS/TMSS/src/tmss/tmssapp/schemas/scheduling_constraints_template-constraints-1.json
+++ b/SAS/TMSS/src/tmss/tmssapp/schemas/scheduling_constraints_template-constraints-1.json
@@ -5,29 +5,6 @@
   "description": "This schema defines the scheduling constraints for a scheduling unit",
   "version": 1,
   "definitions": {
-    "timestamp": {
-      "description": "A timestamp defined in UTC",
-      "type": "string",
-      "pattern": "\\d{4}-[01]\\d-[0-3]\\dT[0-2]\\d:[0-5]\\d:[0-5]\\d(\\.\\d+)?Z",
-      "format": "date-time"
-    },
-    "timewindow": {
-      "type": "object",
-      "description": "A timewindow interval: [from, to)",
-      "properties": {
-        "from": {
-          "$ref": "#/definitions/timestamp"
-        },
-        "to": {
-          "$ref": "#/definitions/timestamp"
-        }
-      },
-      "additionalProperties": false,
-      "required": [
-        "from",
-        "to"
-      ]
-    },
     "distance_on_sky": {
       "type": "number",
       "minimum": 0,
@@ -57,21 +34,21 @@
       "properties": {
         "at": {
           "description": "Start at this moment",
-          "$ref": "#/definitions/timestamp"
+          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timestamp"
         },
         "after": {
           "description": "Start after this moment",
-          "$ref": "#/definitions/timestamp"
+          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timestamp"
         },
         "before": {
           "description": "End before this moment",
-          "$ref": "#/definitions/timestamp"
+          "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timestamp"
         },
         "between": {
           "description": "Run within one of these time windows",
           "type": "array",
           "items": {
-            "$ref": "#/definitions/timewindow"
+            "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timewindow"
           },
           "minItems":0,
           "uniqueItems":true,
@@ -81,7 +58,7 @@
           "description": "Do NOT run within any of these time windows",
           "type": "array",
           "items": {
-            "$ref": "#/definitions/timewindow"
+            "$ref": "http://tmss.lofar.org/api/schemas/commonschematemplate/datetime/1/#/definitions/timewindow"
           },
           "minItems":0,
           "uniqueItems":true,
diff --git a/SAS/TMSS/src/tmss/tmssapp/schemas/templates.json b/SAS/TMSS/src/tmss/tmssapp/schemas/templates.json
index d9ff8dfc4cdc7b601d0741db3bf6f60083ec258e..6e1d2c710101efe1a396935340fcdee899fe3ded 100644
--- a/SAS/TMSS/src/tmss/tmssapp/schemas/templates.json
+++ b/SAS/TMSS/src/tmss/tmssapp/schemas/templates.json
@@ -1,4 +1,8 @@
 [
+  {
+    "file_name": "common_schema_template-datetime-1.json",
+    "template": "common_schema_template"
+  },
   {
     "file_name": "common_schema_template-pointing-1.json",
     "template": "common_schema_template"