As there is no XML parsing module in either the tcl
core distro nor the Tcllib yet, there is a large class
of modules not really nicely includeable into tcllib
(nearly everything xml related). 

A Tcllib XML parsing module would be really nice,
especially if linked to a DOM module using the
::struct::tree (not super efficient but standard). 

Candidates would be the TclXML package from the tclxml
project or a new development. 

A new development could unify the two most used C
extensions in the area (TclXML and tDOM).