The opinion is the first, but may well not be the last, to impose a duty upon lawyers to prevent disclosure of electronic metadata containing client confidences or secrets. Lawyers may therefore wish to consider protecting confidential client information from inadvertent disclosure in "hidden" form just as they need to consider protecting confidential client information from more express forms of disclosure. On the other hand, and at least in the event of inadvertent disclosure, this opinion supports the proposition that metadata may be protected by client confidentiality.