What makes R films R? Ask Prof. Heffner

Prof. Richard Heffner is the baron of ballots that determine whether a movie is rated anywhere from G to X, but Professor Heffner's lips are sealed as to why ''The Razor's Edge'' receives a PG-13 and ''Body Double'' an R.

They stay sealed until the movie industry cries ''action!'' and the cameras roll on a further change in film ratings. But unless the industry decides to expand the ratings to include explanations, Heffner, chairman of the Clarification and Ratings Administration (CARA) of the Motion Picture Association of America, can't even hint that violence may have had something to do with ''Body Double's'' R. And until reasons for explanations are approved, the public will have to settle for guessing whether it's violence, sexuality, profanity, or something else that has prompted the rating.

As the 2,400-member National Association of Theater Owners meets in Washington this week, the controversy over ratings explanations is as hot as buttered popcorn. The group, known as NATO, has been pushing for years to go beyond the stark ratings, and now, to go beyond PG-13, the newest rating, initiated last summer. PG-13 indicates that a movie may not be suitable for children under the age of 13, unless accompanied by an adult. It falls between PG, the most popular category, and R, designed to restrict viewing to those over age 17. G has become the ''Rebecca of Sunnybrook Farm'' of the ratings, a category generally considered too dull by children and adults and normally box-office poison now.

''We had for a long time advocated a rating between PG and R and also advocated the use of (ratings) explanations at the same time,'' says NATO's outgoing president, Joel Resnick. With the introduction of PG-13, the first change in the rating system since its inception in 1968, Resnick says, ''NATO got part of its position but no explanations.'' He says that PG-13 does offer a separate category, so that the more adult ''Terms of Endearment'' and the more violent ''Indiana Jones and the Temple of Doom'' are not lumped together with ''Annie'' and ''Star Trek'' in the same PG category.

In the past, the ratings sometimes resulted in ''having parents misled.'' The new rating is an improvement, Mr. Resnick says, though ''We're still pushing for explanations.''

CARA's czar, Richard Heffner, a Rutgers University professor of communications and public policy, can quote Alexis de Tocqueville at the drop of a ticket stub. Heffner, who edited de Tocqueville's ''Democracy in America,'' quotes the French writer's concern with ''the tyranny of the majority'' to underline his support for the industry's ''voluntary'' ratings system. ''As long as the industry does not choose to give ratings explanations, we will not do it, '' he says. Heffner describes the ratings board as a group outside the industry, asked to administer the system fairly and impartially for the more than 400 movies a year submitted nationally and internationally. CARA's sponsors are NATO , MPAA (Motion Picture Association of America), and the International Film Importers and Distributors of America.

During our interview, Heffner fielded questions about the ratings of several current films and thumbed through ratings-board ballots that indicate specifically why the erotically themed ''Swann in Love'' got an R rather than X, why the porn-and-violence focus of Brian De Palma's ''Body Double'' rated an R instead of an X, and why the film of Somerset Maugham's ''The Razor's Edge'' is offlimits to anyone under 13. Unfortunately, what he said is off the record until or unless the industry decides to give to the public ratings explanations.

Even the board's reasons for the PG ratings of the two Spielberg films that precipitated PG-13 are under seal, although much of the US reading public knows a major factor was the nature and extent of the violence in them. In ''Gremlins, '' the furry animals of the title were killed in blenders and microwave ovens. One scene in ''Indiana Jones'' depicts the heart being ripped out of a living human being. Spielberg himself said that he would put his hands over the eyes of a 10-year-old watching violent scenes in ''Indiana Jones.''

It was a test case and PG-13 was the result. ''PG-13 contains elements ... that lead us to believe parents would want us to give them this more intense advisory,'' Heffner says, ''particularly for kids who are pre-teens.''

Still, some parents may wonder why MPAA-rated films, particularly those starring popular rock singers whom pre-teens and teen-agers swarm to see, seem so laxly rated or the ratings are so poorly enforced. Two cases in point: rock singer Rick Springfield's ''Hard to Hold,'' rated PG even after PG-13 was initiated, and Prince's ''Purple Rain,'' rated R. Industry spokemen point out that the ratings are a voluntary system, and the ratings are not legally enforceable.

Jack Valenti, the silver-haired and silver-tongued chairman of the MPAA, was scheduled to be a featured speaker at Thursday's NATO meeting. Although Mr. Valenti, reached in his Los Angeles MPAA office before his talk, did not want to give a preview of coming attractions and scoop himself, he did indicate that:

While he has been busy polling the studios, as he did before the addition of PG-13 to the ratings, Mr. Valenti says the addition of explanations is ''possible, but nothing is planned. We've talked about it, but nothing's decided in a go-ahead track.'' The results of the polling? ''I know, but it's not transmittable.''

Mr. Valenti says of giving the public explanations of the ratings: ''In all honesty, explanation is very vague - a word may mean one thing to a Texas born-again Baptist, but it may be different language to someone from the Chicago Loop.'' He maintains that words like ''sensuality'' are debatable: ''They don't mean anything until you garment them in specifics. You can't do it in three words or one sentence. Maybe in three paragraphs.''

Valenti says, ''I have no problem with explanations..., if asked for them I would say yes.'' The ratings are ''held together in a consensus of distributors and exhibitors and the ratings have integrity from this consensus,'' he said.

The head of the 5.4 million-member national Parent Teachers Association says film-ratings explanations would be a boon to parents: ''Anytime there is a further definition on what is contained in a film or record, we all have a little piece of direction to help parents make their decision on what they want their children to see and hear,'' says Mrs. Elaine Stienkemeyer, president of the national PTA.

Finally, if all else fails for parents concerned with the US ratings system, there is the British alternative: The British Board of Film Censors has a legal duty to prohibit the admission of children to unsuitable films, and may censor films for adults.

Virtually all films are submitted for ''certification'' there and may receive one of five ratings: U for universal, everyone may attend; PG, parental guidance suggested; ''15'' and ''18,'' for persons not less than 15 or 18, respectively; and Restricted 18, ''for restricted distribution only through segregated premises, to which no one under 18 is admitted.''