WDDX Character data

Is it possible to have the serialize functions in WDDX escape "<" and "&" since at the moment strings containing those characters get serialised correctly but cause the deserialize function to fall over. Normally this wouldn't be a problem since when creating the structures before serialisation I can escape them myself, however I'm currently serialising trees and when I unserialise them to edit a node, expat changes all my &amp; and &lt; to & and <. This means that even though I'm only editing one node in the tree I have to parse every other node to escape the special characters before serialising the structure again. I'm not all that experienced at reading DTD's but from what I can gather since in WDDX strings are not stored between <![CDATA[]]>, then section 2.4 of the XML 1.0 spec (http://www.w3.org/TR/REC-xml#syntax) says that "<" and "&" *must* be escaped. Can anyone more experienced shed some light on whether this is possible/desirable in the php implementation? Is it allowed by the WDDX DTD? Would it break much existing code? Does an #implied CDATA section not have to escape them, just like a real CDATA? and I guess most importantly will it cause problems for other implementations of WDDX? Andrew