Table 1.

Correspondence table between the formal and modified rules of SMILES

Type	Original	Modified
Start of a ring closure	n $\in \{\mathtt{1},\mathtt{2},\dots \}$	&
End of a ring closure	n (same to the start)	& ${}_i$ for the ith ring terminators to the last of a string
Bond followed by atom A	=A (double), #A (triple)	=A or #A form a single character
Terminal character of a molecule	N/A	$
String in a square bracket	[abcde]	[abcde] form a single character