--- a
+++ b/rocaseg/datasets/constants.py
@@ -0,0 +1,44 @@
+from collections import OrderedDict
+
+
+"""
+OAI iMorphics reference classes (DICOM attribute names). Cartilage tissues
+"""
+locations_mh53 = OrderedDict([
+    ('Background', 0),
+    ('FemoralCartilage', 1),
+    ('LateralTibialCartilage', 2),
+    ('MedialTibialCartilage', 3),
+    ('PatellarCartilage', 4),
+    ('LateralMeniscus', 5),
+    ('MedialMeniscus', 6),
+])
+
+
+"""
+Segmentation predictions. Major cartilage tissues. Joined L and M
+"""
+locations_f43h = OrderedDict([
+    ('_background', 0),
+    ('femoral', 1),
+    ('tibial', 2),
+])
+
+
+"""
+Segmentation predictions. Cartilage tissues. Joined L and M
+"""
+locations_zp3n = OrderedDict([
+    ('_background', 0),
+    ('femoral', 1),
+    ('tibial', 2),
+    ('patellar', 3),
+    ('menisci', 4),
+])
+
+
+atlas_to_locations = {
+    'imo': locations_mh53,
+    'segm': locations_zp3n,
+    'okoa': locations_f43h,
+}