+ <xpath expr="//group/field[@name='membership_date_from']" position="attributes">
+ <attribute name="attrs">{'required':['&',('membership','=',True),('membership_date2date','=',False)]}</attribute>
+ </xpath>
+ <xpath expr="//group/field[@name='membership_date_to']" position="attributes">
+ <attribute name="attrs">{'required':['&',('membership','=',True),('membership_date2date','=',False)]}</attribute>
+ </xpath>