call.rng in cpee-2.1.52

- old
+ new

@@ -1,10 +1,12 @@
 <element xmlns="http://relaxng.org/ns/structure/1.0" xmlns:rngui="http://rngui.org" rngui:version="1.2" ns="http://cpee.org/ns/description/1.0" name="call" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
   <attribute name="id" rngui:label="ID" rngui:default="javascript:get_free_id()">
     <data type="string" rngui:readonly="true"/>
   </attribute>
   <attribute name="endpoint" rngui:label="Endpoint">
-    <data type="string"/>
+    <data type="string">
+      <param name="pattern">^[a-z_][a-zA-Z0-9_]*$</param>
+    </data>
   </attribute>
   <element name="parameters" rngui:header="Properties">
     <element name="label" rngui:label="Label">
       <data type="string" rngui:label="Short description of the task"/>
     </element>