public static function overlapping_meta_keys() {
		return apply_filters(
			'invp_overlapping_keys',
			array(
				'body_style'      => 'style',
				'make'            => 'make',
				'model'           => 'model',
				'year'            => 'model_year',

				'availability'    => 'availability',
				'color_base'      => 'colors',
				'condition'       => 'condition',
				'cylinders'       => 'cylinders',
				'drive_type'      => 'drive_type',
				'fuel'            => 'fuel',
				'location'        => 'location',
				'propulsion_type' => 'propulsion_type',
				'transmission'    => 'transmission',
				'type'            => 'type',
				'wholesale'       => 'availability', // Wholesale is a meta field and also a valid Availability taxonomy term.

				'condition_boat'  => 'condition_boat',
				'engine_count'    => 'engine_count',
				'engine_make'     => 'engine_make',
				'engine_model'    => 'engine_model',
				'horsepower'      => 'horsepower',
				'hull_material'   => 'hull_material',
			)
		);
	}