This is just a documentation error, since I'm sure everybody who reads it will understand what you mean, but in the steps for replacing data (for a CharacterData instance - see http://dvcs.w3.org/hg/domcore/raw-file/tip/Overview.html#concept-cd-replace) steps 9 and 10 are exactly identical. They both state:
"For each range whose start node is node and start offset is greater than offset plus count, increase its start offset by the number of code units in data, then decrease it by count."
I believe that your intentions were for step 10 to say:
"For each range whose END NODE is node and END OFFSET is greater than offset plus count, increase its start offset by the number of code units in data, then decrease it by count."
I just want to point it out so that it can be fixed in the next version of the specification.
(The last start offset also had to be replaced.)
<span title=concept-range-start-node>end node</span>
xref is wrong