EDITORIAL : TV'S NEW GUIDE IF A SHOW IS TO BE RATED PG, PARENTS NEED TO KNOW WHY.

Though they haven't been issued yet, television ratings already are generating controversy.

U.S. Rep. Ed Markey, D-Mass., who wrote the V-chip law mandating TV ratings, is criticizing the industry proposal expected to be announced within two weeks for failing to give parents the facts they need to decide what's right for their children.

The industry group is widely believed to be considering adding categories to the existing motion picture ratings system for television. In addition to G, PG and PG-13, the television proposal may include PG-17 and either PG-7, PG-8 or PG-9, indicating parental guidance is advised for children under the ages cited.

Markey said he had intended that the new TV-rating provision of the Telecommunications Act would give parents a programming guide that is detailed and descriptive as to language, sex and violence.

Markey has a point. To be helpful for parents, the ratings should contain enough basic information to guide them on why the show might be inappropriate for their children. A system similar to that used for motion pictures that would lump language, sex and violent material together in groups doesn't help parents sort out what might be inappropriate with a particular show.

However, no guide could ever cover everything. As we have said before, ultimately, decisions of taste and values belong to parents and other responsible viewers. The bottom line is, ratings and V chips - no matter how skimpy or detailed - shouldn't replace parental judgment.