A magnum of the old, a shot of the new, Charlotte Ford's updated etiquette does, however, seek out a comfortable, considerate meeting ground between the old and the new generations. How to bed the unwed in Mother's house? Mother's rules prevail. ""Living together and having a child""? For grandparents-to-be, breaking the ""good news"" can be grim; to fend off condolences, try ""a positive declaration."" Elsewhere, too, there are signs of the times: it's definitely de rigueur to request a doggie bag in a restaurant, to use plastic cups and plates for informal dos, to stuff a napkin under the chin when eating chicken with one's fingers. Otherwise, though, this is ye olde basic reference--with proper formats for everything from Bar Mitzvah announcements to coat-of-arms stationery, and strategems for everything from answering the phone to dipping bread into the gravy. And if you're invited to a large reception at the White House, ""you may send your regrets with no explanation."" Exhaustive--but one never knows.