diff --git a/version/version.go b/version/version.go
index 72b6e9b8..62bf8bbb 100644
--- a/version/version.go
+++ b/version/version.go
@@ -79,4 +79,11 @@ func Decode(jsonBytes []byte) (PluginInfo, error) {
 	return &info, nil
 }
 
+// Legacy PluginInfo describes a plugin that is backwards compatible with the
+// CNI spec version 0.1.0.  In particular, a runtime compiled against the 0.1.0
+// library ought to work correctly with a plugin that reports support for
+// Legacy versions.
+//
+// Any future CNI spec versions which meet this definition will be added to
+// this list.
 var Legacy = PluginSupports("0.1.0", "0.2.0", "0.3.0")