Chemical Features Specific or Comparable

In order to describe the levels of universality and specificity of chemical features, a simple layer model is proposed to allow referral to these properties more easily. Table 6.1 shows a proposed classification of abstraction layers of chemical features A lower level corresponds to higher specificity and therefore lower universality. 

Below are some examples of chemical features according to the specificity of this layer model  

4 Chemical functionality (positive ionizable area, lipophilic contact) without geometric constraint +++ - 

3 Chemical functionality (hydrogen bond donor, acceptor) with geometric constraint ++ + 

2 Molecular graph descriptor (atom, bond) without geometric constraint — ++ 

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