'feature', 'columns' => array( 'feature_id' => 'feature_id', 'chromosome_id' => 'feature_id', ), ); $description['foreign keys']['genotype'] = array( 'table' => 'genotype', 'columns' => array( 'genotype_id' => 'genotype_id', ), ); $description['foreign keys']['cvterm'] = array( 'table' => 'cvterm', 'columns' => array( 'type_id' => 'cvterm_id', ), ); return $description; }