Table 1.

ONZ class coverage by uni-, bi- and tetramolecular tetrads

Tetrads	O+	O-	N+	N-	Z+	Z-	Total
Unimolecular	475	83	104	51	6	8	727
Bimolecular	87	10	25	17	101	98	338
Tetramolecular	332	48	-	-	-	-	380
Total	894	141	129	68	107	106	1445