RESIDUE   ETD      4
CONECT      C10    2 C11  H10 
CONECT      C11    2 C10  H11 
CONECT      H10    1 C10 
CONECT      H11    1 C11 
END   
HET    ETD              4
HETNAM     ETD ETHENYLENE GROUP
FORMUL      ETD    C2 H2