--- a
+++ b/pathaia/datasets/errors.py
@@ -0,0 +1,66 @@
+# coding: utf8
+"""
+A module to handle datasets errors.
+
+Enable catching of level and filter accesses.
+"""
+
+
+class Error(Exception):
+    """
+    Base of custom errors.
+
+    **********************
+    """
+
+    pass
+
+
+class UnknownSplitModeError(Error):
+    """
+    Raise when trying to split a dataset with an unknown option.
+
+    *********************************************************
+    """
+
+    pass
+
+
+class InvalidDatasetError(Error):
+    """
+    Raise when trying to perform operation on a dataset with bad properties.
+
+    ************************************************************************
+    """
+
+    pass
+
+
+class MissingArgumentError(Error):
+    """
+    Raise when trying to perform operation on a dataset with bad properties.
+
+    ************************************************************************
+    """
+
+    pass
+
+
+class InvalidSplitError(Error):
+    """
+    Raise when trying to perform operation on a dataset with bad properties.
+
+    ************************************************************************
+    """
+
+    pass
+
+
+class TagNotFoundError(Error):
+    """
+    Raise when trying to reach a class not present in the dataset.
+
+    ************************************************************************
+    """
+
+    pass