Changes

replace value of node /n with <a><b/></a>'newValue'

All As a result all descendants of /n are deleted and the given subtree text is inserted as the only child. Note that the result of the insert sequence is either a single text node or an empty sequence. If the insert sequence is empty all descendants of the target are deleted. Consequently replacing the value of a node leaves the target with either a single text node or no descendants at all.