--- a/RelaxNG/publiset.rnc	mar. mai 19 18:32:20 2015 +0200
+++ b/RelaxNG/publiset.rnc	ven. mai 22 17:35:52 2015 +0200
@@ -13,7 +13,8 @@
 version.attribute = attribute version { "1.0" }
 
 publiset.content =
-   (composition | selection)+
+   composition
+ | selection
 
 
 # =============================================================================
@@ -211,7 +212,7 @@
 }
 
 composition.attributes =
-   composition.id.attribute
+   composition.id.attribute?
  & lang.attribute?
  & path.attribute?
  & pi-source.attribute?
@@ -259,7 +260,7 @@
 }
 
 selection.attributes =
-   selection.id.attribute
+   selection.id.attribute?
  & lang.attribute?
  & path.attribute?
 selection.id.attribute = attribute id { xsd:NMTOKEN }