Added sentences to expand on justification usage

datadesc/index.html

@@ -379,8 +379,10 @@ <h4 id="justifications">Mapping Justifications</h4>
           one which matches compounds on their full chemical structure, i.e.
           including their charges and stereo-chemistry. </p>
         <p> The ability to classify linksets for use under different scientific
-          lenses relies on the justification given in the linkset. A set of
-          vocabulary terms for providing justifications are given in <a href="#appendix-link-justifications">Appendix
+          lenses relies on the justification given in the linkset, i.e. the
+          notion of operational equivalence, or alternative the interpretation,
+          that is captured by the links. A set of vocabulary terms for providing
+          justifications are given in <a href="#appendix-link-justifications">Appendix
             B.2</a>. </p>
         <h4 id="mapping-example">Example</h4>
         <p> The following example declares that the ChemSpider α-Ketoisovaleric