
   if (logic)
     (commands)
   end

   or:

   if (logic)
     (commands)
   else 
     (commnds)
   end

   logical block.  The commands are performed subject to the logical
   condition.  The syntax is simplified C:  
   examples: (x = 6), (x < 6) , (x ! 6), ((x = 6) | (x > 10))

   there are no delimiter characters.

   See also: for, macro

   