Five controversial documentaries to air on PBS

While the commercial networks are emphasizing safe and jazzy news-magazine shows, public broadcasting is moving boldly ahead with varied, full-length documentaries on controversial subjects. This week, for instance, four PBS premi`eres plunge into uncharted waters with energy and curiosity. And another fine show is being repeated. Standoff in Mexico (Tuesday, 9-10 p.m., check local listings) deals with a potentially explosive situation seldom noted by US citizens: the alleged fraud and corruption in last summer's Juarez and Sonora elections, following the campaign of Aldalberto Rosas Lopez, the right-wing PAN candidate who lost to Felix Valdez, the PRI candidate. Like most ``Frontline'' projects, ``Standoff'' is a fearless attempt to bring perspective to a complex issue. It doesn't pretend to have all the answers, but it will help viewers who are trying to understand.

Witness to War: Dr. Charles Clements (Tuesday, 10-10:30 p.m.), which won an Academy Award last week, is the simple tale of one man's personal odyssey from gung-ho combat pilot in Vietnam to noncombatant doctor behind rebel lines in El Salvador. With Clements himself reading diary entries, this American Friends Service Committee film traces a soul-searching voyage of commitment.

South Africa Under Siege (Tuesday, 10:30-11 p.m.) is not a look at apartheid. Instead it takes viewers inside the headquarters of the outlawed African National Congress (ANC), the black organization led by the imprisoned Nelson Mandela that is likely to play an important part in the South Africa's future. According to producer Stephen Talbot, ANC members are ``reluctant revolutionaries.'' The group, begun 74 years ago as a nonviolent civil-rights movement, was forced into exile 25 years ago. The documentary takes viewers to ANC headquarters in Zambia and Botswana and tries to determine exactly who ANC members are and what they stand for.

Spain: 10 Years After/A Reporter's Notebook (Wednesday, 9-10 p.m.) gives a unique glimpse of the country's decade of transition to democracy since Franco. Pulitzer Prize-winning journalist John Darnton interviews political and cultural leaders in Madrid, the Basque country, Andalusia, and elsewhere. The wide-ranging conversations include sessions with a religious leader, former Prime Minister Adolfo Suarez, and filmmaker Carlos Saura.

`A' is for Atom, `B' is for Bomb: A Portrait of Dr. Edward Teller (Tuesday, 8-9 p.m.) is a repeat of a ``Nova'' segment on the nuclear pioneer's career from his youth in Hungary to his key role in US weapons research.