Thanks to everyone who responded on- and off-list. I tried the open as zip solution and yes, there was a file with the content but I don't know enough xml to do anything with it.
Re: backups. I use Time Machine (Mac). Unfortunately, the client held onto the file for several months, so those backups are gone. Finally, the client doesn't want anyone outside their organization or my agency's organization to look at the file. The agency had an inhouse IT person clean it up and now it opens but all the equations are gone. Sigh. Thanks again! Pat
