6 MORE FOR NAFTA . . . SORT OF

The North American Free Trade Agreement between the U.S., Canada and Mexico seems to be chugging along so smoothly that six more Central American countries may want in. At a confab of foreign ministers in Costa Rica, officials of Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and Panama agreed Tuesday to seek provisional memberships -- as the first step to full participation -- in NAFTA. They'll make the pitch in December at a Miami summit of Central American presidents to be hosted by President Clinton.