Description of image file

{ SEARCH
 { DEPTH FIRST BY c_alias [, c_alias]...
 [ ASC | DESC ]
 [ NULLS FIRST | NULLS LAST ]
 | BREADTH FIRST BY c_alias [, c_alias]...
 [ ASC | DESC ]
 [ NULLS FIRST | NULLS LAST ]
 }
 SET ordering_column
}