diff --git a/cdfm/consts.py b/cdfm/consts.py
index 40a96af..cb81d2d 100644
--- a/cdfm/consts.py
+++ b/cdfm/consts.py
@@ -1 +1,9 @@
 # -*- coding: utf-8 -*-
+"""Constants
+"""
+LABEL = 'label'
+QID = 'qid'
+EID = 'eid'
+CIDS = 'cids'
+FEATURES = 'features'
+PROXIMITIES = 'proximities'
diff --git a/cdfm/data.py b/cdfm/data.py
new file mode 100644
index 0000000..ad52cc1
--- /dev/null
+++ b/cdfm/data.py
@@ -0,0 +1,8 @@
+# -*- coding: utf-8 -*-
+"""Definition of records in dataset.
+"""
+from collections import namedtuple
+from .consts import LABEL, QID, EID, CIDS, FEATURES, PROXIMITIES
+
+
+Row = namedtuple('Row', (LABEL, QID, EID, CIDS, FEATURES, PROXIMITIES))
diff --git a/cdfm/types.py b/cdfm/types.py
index a04f0d2..1c52538 100644
--- a/cdfm/types.py
+++ b/cdfm/types.py
@@ -1,8 +1,10 @@
 # -*- coding: utf-8 -*-
 """Type annotations.
 """
-from typing import Dict, Union
+from typing import Dict, List, Union
+from .data import Row
 
 
+Dataset = List[Row]
 EntityID = Union[int, str]
 EntIndMap = Dict[EntityID, int]