Let me say this again in a different way. Anyone who thinks that they can use the DOM to gain direct access to the information contained in topic map documents is totally in the dark about the nature of topic maps and about the meaning of the information contained in topic map documents. It is based on a false assumption that is pervasive in Web-land, and this is the reason why the error is so very common. The false assumption is that the syntax of an XML document is also always the API to the information that it contains. While that assumption may work for comparatively simple kinds of information, it cannot work for n-dimensional information.
Topics are inherently n-dimensional.
The connections between topics are inherently n-dimensional. The conections between the connections between the topics are inherently n-dimensional. Any interchange syntax for topic maps necessarily squashes all these dimensions into a single string. There is not now, nor can there ever be, any practical way for topic map information, which is inherently multidimensional, to be represented as a single string of characters in such a way as to allow applications to skip the step of reconstituting the topic map graph and still understand the information contained in the topic map document. XTM 1.0 won't answer this very good question.