[chemical substances]
   compounds
     Class lipids
       Class phospholipids
         Class phosphoglycerides [RC(=O)OCH2CH(OC(=O)R)CH2OP(=O)(OR)2]
           Class lecithins [RC(=O)OCH2CH(OC(=O)R)CH2OP(=O)(OH)OCH2CH2N+(CH3)3]