<P> Takes a list of concepts which are linked by relations, and selects specified 
  Features from them which are collected in the output Concept, via a join on 
  the concepts of the chain. To be more precise: Recall that Relations are only 
  defined by the user between initial Concepts of a Case. Suppose there is a chain 
  of initial Concepts <var>C<sub>1</sub> ,..., C<sub>n</sub></var> such that between 
  all <var>C<sub>i </sub></var>and <var>C<sub>i+1</sub> ,1&lt;= i < n</var>, <var>C<sub>i</sub></var> 
  is the <I>FromConcept</I> of the i-th Relation and <var>C<sub>i+1</sub></var> 
  is its <I>ToConcept</I>. These Concepts may be modified in the Case being modelled, 
  to result in new Concepts <var>C'<sub>1</sub>,...,C'<sub>n</sub></var> , where 
  some <var>C'<sub>i</sub></var> may be equal to <var>C<sub>i</sub></var>. However, 
  the BaseAttributes that correspond to the Relation keys are still present in 
  the new Concepts . By using their names, this operator can find the key Columns 
  and join the new Concepts . 
<P> The parameter table below refers to this explanation. Note that all input 
  Concepts are the new Concepts <var>C'<sub>i</sub></var>, but all input Relations 
  link the original Concepts <var>C<sub>i</sub></var>. 
<P> <BR>
  <BR>
<P> 
PARAMETERDESCRIPTION
TheInputConcept:Concept <var>C'<sub>1</sub></var> (inherited)
TheConcepts:Concepts <var>C'<sub>2</sub> ,..., C'<sub>n</sub></var>
TheRelations:they link <var>C<sub>1</sub> ,..., C<sub>n</sub></var>
TheChainedFeatures:from <var>C'<sub>1</sub> ,..., C'<sub>n</sub></var>
TheOutputConcept:inherited