Usually our interest in comparing the content of texts is to establish whether the edited version is a faithful rendering of the original. We acknowledge authors' rights to change the meaning of what they originally wrote, assuming they have changed their minds on the matter. Outside editors are not given the same licence. They are expected to transmit faithfully the meaning of the original text. In many cases, it may not matter if an editor takes liberties with the content of a text. If details of a story are changed in re-writing for children, it is unlikely to matter. However, more substantial changes may, even in fictional writing, remove the edited version unacceptably far from reality or from the author's original. Adding and deleting information or restructuring connections in a text can produce a misleading version (Davison et al., 1980)