GOOD FENCES may or may not make good neighbors, but shared walls, particularly when the people living on different sides park their electronic equipment against them, do not. Miss Manners would therefore like to spell out some special rules of neighborliness, based on city living.

Urban neighborliness means that one has an obligation to notice disreputable characters who seem to be fooling around with a neighbor's house, and to report them. Urban neighborliness also means that one has an obligation not to notice disreputable characters whom one's neighbor has invited to his house for purposes of fooling around.

A person who lives in the city should take in his neighbor's mail and newspaper when requested, so that the house whose tenant is absent will not seem deserted. A person who lives in the city should not take in the papers or magazines of those living in nearby apartments if the owners are merely late risers.

Friendly gossip about the neighbors is as much a part of city as country living. It is not, however, friendly to pass on possibly damaging speculation about ones neighbors, particularly if interviewed about them by the Federal Bureau of Investigation.

Greater individuality is permitted in the city than in small towns or suburbs. Provided that your hours, your taste in music and the color you paint your house suit the wishes of the person next door, there should be no conflicts. And if there are, an impartial arbitrator is no further away than the corner squad car.

Miss Manners Responds

Q: Two friends, currently living together without benefit of clergy, recently sent me a hand-lettered wedding invitation, R.S.V.P. The invitation is from both of them, not from either set of parents. The problem is, to whom do I address the R.S.V.P.?

A: The obvious thing is, of course, to answer the people who asked the question. However, Miss Manners senses you have something more in mind here than simply telling the people who invited you that you will or will not attend. Perhaps it is the simple pleasure of participating in you friends' bliss by suggesting to them that they have made some terrible error. The best way to do this is to address your reply to the bride's parents. Won't they be surprised!