custom post types and custom fields

In WordPress – content is stored in wp_posts Meta data is stored in wp_postmeta

bw_register_post_type( 'oik-plugins', $post_type_args );
bw_register_field( "_oikp_slug", "text", "Plugin slug", array( '#hint' => "_oikp_slug" ) ); 
bw_register_field_for_object_type( "_oikp_slug", "oik-plugins" ); 
bw_register_post_type( "oik_api" );
bw_register_field( "_oik_api_plugin", "noderef", "Plugin ref", array( "#type" => "oik-plugins" )); 
bw_register_field_for_object_type( "_oik_api_plugin", "oik_api" );
 

Taxonomies and their relationships with posts take up 3 more tables.