here are columns in BASE and COMPARE with different modes !!
#&gt; All rows are shown in table below
#&gt; 
#&gt;   ================================
#&gt;    VARIABLE  MODE.BASE  MODE.COMP 
#&gt;   --------------------------------
#&gt;       v1     character   numeric  
#&gt;   --------------------------------
#&gt; 
#&gt; There are columns in BASE and COMPARE with different classes !!
#&gt; All rows are shown in table below
#&gt; 
#&gt;   ==================================
#&gt;    VARIABLE  CLASS.BASE  C