Description of the illustration cell_assignment.eps

measure_column [ { { condition
                   | expr
                   | single_column_for_loop
                   }
                     [, { condition
                        | expr
                        | single_column_for_loop
                        }
                     ]...
                 | multi_column_for_loop
                 }
               ]

Note: The outer square brackets are part of the syntax.
      In this case, they do not indicate optionality.