diff --git a/dakota_interface.py b/dakota_interface.py
index f605544..e110604 100644
--- a/dakota_interface.py
+++ b/dakota_interface.py
@@ -73,15 +73,21 @@ def interface(fn_json_args):
         # Calculate actual responses
         for k, v in interface_args['post_process'].items():
             # print('')
-            # print('label:', v[0])
-            bp = ms.getBeamProperty(v[0])
-            # print('bp:', bp)
-            if v[1] == 'self':
-                r = bp
-            elif v[1] == 'abs_rel_diff':
-                r = np.abs((bp - v[2]) / v[2])
-            else:
-                r = eval('dpf.{0}'.format(v[1]))(bp, v[2])
+            # print('v[0]:', v[0])
+            # print(type(v[0]).__name__)
+            if type(v[0]).__name__ == 'str' or type(v[0]).__name__ == 'unicode':
+                bp = ms.getBeamProperty(v[0])
+                # print('bp:', bp)
+                if v[1] == 'self':
+                    r = bp
+                elif v[1] == 'abs_rel_diff':
+                    r = np.abs((bp - v[2]) / v[2])
+                else:
+                    r = eval('dpf.{0}'.format(v[1]))(bp, v[2])
+            elif type(v[0]).__name__ == 'list':
+                bps = [ms.getBeamProperty(s) for s in v[0]]
+                r = eval('dpf.{0}'.format(v[1]))(bps, v[2])
+
             results[k].function = r