diff --git a/config.yml b/config.yml
index f3bf264..4ac28e8 100644
--- a/config.yml
+++ b/config.yml
@@ -67,8 +67,10 @@ layers:
             start: "ICME_START_TIME"
             end:   "MO_END_TIME"
             l1:
-                venus:   "VEX"
-                mercury: "MESSENGER"
+                venus:
+                    constraints: [ { SC_INSITU: ["VEX"] } ]
+                mercury:
+                    constraints: [ { SC_INSITU: ["MESSENGER"] } ]
 
 
 inputs:
diff --git a/web/run.py b/web/run.py
index 9e09fa2..f624fd5 100755
--- a/web/run.py
+++ b/web/run.py
@@ -740,10 +740,19 @@ def get_catalog_layers(input_slug, target_slug):
     :param target_slug: 
     :return: 
     """
-    SC_INSITU_INDEX = 1
     START_INDEX = 2
     STOP_INDEX = 4
     import json
+
+    def _get_index_of_key(_data, _key):
+        index = None
+        try:
+            index = _data['columns'].index(_key)
+        except ValueError:
+            log.error("Key %s not found in columns of %s" % (_key, _data))
+            raise
+        return index
+
     catalog_layers = {}
     for config_layer in config['layers']:
         if 'data' not in config_layer:
@@ -755,17 +764,30 @@ def get_catalog_layers(input_slug, target_slug):
                 continue
             if target_slug not in cl_datum[input_slug]:
                 continue
-            # SC_INSITU is the name of the key in the JSON file
-            sc_insitu = cl_datum[input_slug][target_slug]
+            constraints = cl_datum[input_slug][target_slug]['constraints']
             #log.debug('Inspect B')
             with open(get_path("../data/catalog/%s" % cl_datum['file'])) as f:
                 json_data = json.load(f)
+
                 for json_datum in json_data['data']:
-                    if json_datum[SC_INSITU_INDEX] != sc_insitu:
+                    validates_any_constraint = False
+                    for constraint in constraints:
+                        validates_constraint = True
+                        for key, possible_values in constraint.iteritems():
+                            actual_value = json_datum[_get_index_of_key(
+                                json_data, key
+                            )]
+                            if actual_value not in possible_values:
+                                validates_constraint = False
+                                break
+                        if validates_constraint:
+                            validates_any_constraint = True
+                            break
+                    if not validates_any_constraint:
                         continue
                     catalog_layers[config_layer['slug']].append({
                         'start': json_datum[START_INDEX],
-                        'stop': json_datum[STOP_INDEX],
+                        'stop':  json_datum[STOP_INDEX],
                     })
             #log.debug('Inspect C')
 
--
libgit2 0.21.2