[chemical substances]
   compounds
     Class nucleotides [HOP(=O)(OH)OCH2CH(O~)CH(OH)CH(Y)CH(base)~ (Y=H or OH)]
       109 Class deoxyribonucleotides [HOP(=O)(OH)OCH2CH(O~)CH(OH)CH2CH(base)~]
       109 Class ribonucleotides [HOP(=O)(OH)OCH2CH(O~)CH(OH)CH(OH)CH(base)~]
       111 Class oligonucleotides