+
+ foreign_keys => [
+ depended_item => {
+ class => 'SL::DB::RequirementSpecItem',
+ key_columns => { depended_item_id => 'id' },
+ },
+
+ depending_item => {
+ class => 'SL::DB::RequirementSpecItem',
+ key_columns => { depending_item_id => 'id' },
+ },
+ ],