--- a/cubicweb/web/schemaviewer.py	Tue Jun 04 09:35:47 2019 +0200
+++ b/cubicweb/web/schemaviewer.py	Tue Jun 11 09:40:12 2019 +0200
@@ -140,7 +140,7 @@
         first = True
 
         rel_defs = sorted(eschema.relation_definitions(),
-                          key=lambda el: (el[0].type, el[0].cardinality))
+                          key=lambda el: el[0].type)
 
         for rschema, targetschemas, role in rel_defs:
             if rschema.type in skiptypes: