WASHINGTON (AP) _ Parents cannot rely on the new TV ratings to warn them about many of the shows that contain violence, sex or crude language, according to a study released today.

Since Oct. 1, 1997, when ABC, CBS, Fox and most cable networks began using new detailed TV ratings, the letters ``V,'' ``S,'' ``L'' and ``D'' have appeared on TV screens alongside the older age-based ratings.

The letters are intended to warn of violence, sex, crude language and suggestive dialogue.

But the study found that 79 percent of shows with violence did not carry a ``V'' notation.

In addition, 92 percent of shows with sex did not have an ``S,'' while 91 percent with adult language did not use an ``L'' and 83 percent of shows with suggestive dialogue did not carry a ``D.''

The report was commissioned by the Kaiser Family Foundation, which is interested in entertainment's' impact on society.

The report said 81 percent of children's shows that contain violence did not carry the ``FV'' notation, which is supposed to warn parents of fantasy violence like that depicted in cartoons.

The study, however, said the TV industry is accurately applying the age-based ratings to shows.

TV industry representatives acknowledged a need for improving how the labels are applied but didn't believe the ratings need to be overhauled.

``We're willing to listen to suggested ways of improving the labeling, but the system does not need to be changed.'' said National Association of Broadcasters spokesman Dennis Wharton.

Rep. Edward Markey, D-Mass., and others suggested that an independent ratings review board of industry representatives and parents resolve the problems pointed out in the study. The group is to meet in November.

Researchers at the University of California, Santa Barbara, conducted the study.

They analyzed 1,147 randomly selected programs that were eligible for ratings, airing in the winter and spring between 7 a.m. and 11 p.m. on ABC, CBS, NBC and Fox stations, cable networks HBO, USA, TNT, Lifetime and Nickelodeon and independent TV station KTLA in Los Angeles.

``The vast majority of shows that contain sex and violence are not being flagged with the labels,'' said Vicky Rideout, director of the foundation's program on entertainment media and public health. ``Yet parents find these labels the most useful part of the ratings system.''

The ratings are designed to work with blocking technology, dubbed the v-chip, that will let viewers block shows based on their ratings. TV sets containing the v-chip will be available next year.

Given the findings, v-chip TV sets offer parents ``only a modest degree of help in identifying potentially harmful violence they might wish to screen from their children's eyes,'' the study concludes.

``Parents using the v-chip should know that most sex and violence on TV will still be coming through,'' Rideout said.

But most parents _ 55 percent _ who use the ratings think any show with violence is supposed to get a ``V'' label, according to a poll commissioned by the foundation.

In general, shows that did not get a ``V'' or ``S'' had much lower levels of sex and violence than shows that did carry the notations. But that was not always the case.

For example, one episode of CBS' ``Walker Texas Ranger,'' while rated ``TV-14,'' did not carry an added ``V'' symbol even though the show included the stabbing of two guards on a bus, an assault on a church by escaped convicts who threatened to rape a nun, a shooting of one convict and the beating of another.

On the Lifetime cable channel, a ``TV-PG''-rated Danielle Steele movie, ``Family Album,'' did not carry a ``S'' label, even though it contained scenes of couples making love.

One reason why some programs do not carry the ``V,'' ``S,'' ``L'' and ``D'' notations is because programs rated ``TV-G,'' suitable for all ages, do not carry the labels even if they contain some level of violence, sex or crude language.

Another reason: Some programs rated ``TV-PG'' or ``TV-14'' do not carry the additional labels when the level or intensity of violence, sex or crude language in a given show was less than what is provided for under the age-based rating.

For example, a show rated ``TV-14'' contains ``intense'' violence and would get a ``V'' label for that, but the show would not necessarily get a ``V'' for ``moderate'' violence.

Also, there are other reasons including industry judgment calls, the fact that NBC uses only age-based ratings and not the letter notations, and that films can be shown with movie ratings, such as ``R'' and ``PG-13''.