Improve values of readonly attribute

trytond/ir/ui/form.rnc

@@ -100,7 +100,7 @@ attlist.field &= [ a:defaultValue = "1" ] attribute xfill { "0" | "1" }?
 attlist.field &= attribute help { text }?
 attlist.field &= attribute width { text }?
 attlist.field &= attribute height { text }?
-attlist.field &= attribute readonly { text }?
+attlist.field &= attribute readonly { "0" | "1" }?
 attlist.field &=
   [ a:defaultValue = "0" ] attribute tree_invisible { "0" | "1" }?
 attlist.field &= attribute mode { text }?

trytond/ir/ui/form.rng

@@ -346,7 +346,12 @@
   </define>
   <define name="attlist.field" combine="interleave">
     <optional>
-      <attribute name="readonly"/>
+      <attribute name="readonly">
+        <choice>
+          <value>0</value>
+          <value>1</value>
+        </choice>
+      </attribute>
     </optional>
   </define>
   <define name="attlist.field" combine="interleave">

trytond/ir/ui/tree.rnc

@@ -16,7 +16,7 @@ attlist.tree &=
   [ a:defaultValue = "0" ] attribute toolbar { "0" | "1" }?
 field = element field { attlist.field, empty }
 attlist.field &= attribute name { text }
-attlist.field &= attribute readonly { text }?
+attlist.field &= attribute readonly { "0" | "1" }?
 attlist.field &=
   attribute widget {
     "char"

trytond/ir/ui/tree.rng

@@ -72,7 +72,12 @@
   </define>
   <define name="attlist.field" combine="interleave">
     <optional>
-      <attribute name="readonly"/>
+      <attribute name="readonly">
+        <choice>
+          <value>0</value>
+          <value>1</value>
+        </choice>
+      </attribute>
     </optional>
   </define>
   <define name="attlist.field" combine="interleave">