An X-dummy atom inside a molecular fragment signifies an available anchor, allowing the fragment to connect with another fragment. A molecular fragment can have multiple X-dummy-atoms. The lea-string notation is used to record the combination information of different molecular fragments for representing a molecule. As displayed in Table , the leastring of the designed molecule indicates that propyne is the combination of the fragment 1 and 2 , with the third atom of the first fragment 3 linked to the first atom of the second fragment 1. For further details regarding the grammar of the lea-string notation, please refer 190 to the handbook of LEA3D.