func Begin () {
trc = 1;
}
func OnLineHeader () {
ntrc = LH.NumTrc;
}
func OnTrace () {

	if ( trc == 1 ) {
		srx = Tr.SrPtXC;
		sry = Tr.SrPtYC;
		print (srx," ",sry,"\n");
	}
	trc = trc + 1;
	if ( trc > ntrc ) trc = 1;
}