Hi

from http://pubsvn.ez.no/doxygen/4.0/html/ezurltype_8php-source.html#l00289
and from testing i understand that ezurl datatype fromstring will not remove the url when an empty string is passed. that seems unintented.

Steps to reproduce

create a node with an ezurl attribute, try to set the url datatype with the fromstring method with a string, try to unset the url datatype with the same method and an empty string.