The format of the fragments is: 

Element x y z

Atom1 Atom2 Connection
Where Element is either the symbol of the element, or a special identifier to allow multiple molecules fragments together. Atom1 and Atom2 are the index number of the atoms in the bonds (1-indexed). The Connection compenent is the type of bond the atoms have. The possible bonds are in the set {'1', '2', '3', 'Ar'} where 'Ar' stands for aromatic.

Cores

X/R Groups

Aryl Groups