Description of image file

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.