diff --git a/codearchiver/core.py b/codearchiver/core.py
index f5ba43c..510bd5c 100644
--- a/codearchiver/core.py
+++ b/codearchiver/core.py
@@ -83,7 +83,11 @@ class MetadataField:
 
 
 class Metadata(list[tuple[str, str]]):
-	'''Metadata (key-value mapping, possibly with repeated keys) of a file produced by a module'''
+	'''
+	Metadata (key-value mapping, possibly with repeated keys) of a file produced by a module
+
+	Fields are inherited. Subclasses meant to be usable should define their own version; the 'Metadata version' field is set by `Module.create_metadata` and collects all declared versions.
+	'''
 
 	fields: tuple[MetadataField] = (
 		MetadataField('codearchiver version', required = True, repeatable = False),