see each call description for details

    namespace definitions, 
    first parameter is the current object 
    othe parameters:
    with single paramter ( element name ) it will return  
    id ( not the actual URI) of the namesapce and with two parameters will set namespace
    to specific element name
    and without parameters it will return the whole namespaces hashref

   Maxim Grigoriev (FNAL)  2007, maxim@fnal.gov