setSerializationLevel(userData,fullXML,escapeEntities,userDataAsCData,DTD)
Required library edition: 
Required library file: dhtmlxtree_xw.js
configure XML serialization
- userData - enable/disable user data serialization
- fullXML - enable/disable full XML serialization
- escapeEntities - convert tag brackets to related html entitites
- userDataAsCData - output user data in CDATA sections
- DTD - if specified, then set as XML's DTD