Abu Sayyaf guerrillas continued their campaign of terror in Basilan, abducting 37 Filipinos Aug. 2 and later beheading ten. The rest were freed in the face of an army assault. Such violence by Abu Sayyaf and other guerrilla groups has made travel risky in the southern Philippines, but the central and northern portions of the archipelago are relatively safe, if you travel with caution and use common sense.