+=item *
+
+Prices have defined information channels for missing and invalid, but it would
+be deriable to have more information flow. For example a limited offer might
+expire in three days while the record is valid for 20 days. THis mismatch is
+impossible to resolve automatically, but informing the user about it would be a
+nice thing.
+
+This can also extend to diagnostics on class level, where implementations can
+call attention to likely misconfigurations.
+