Ticket #21391: plugin.php

<?php
/**
 * Plugin Name: Custom Attachment Taxonomies
 */

function ds_register_example_attachment_taxonomies() {
        register_taxonomy( 'attachment_category', 'attachment', array(
                'hierarchical' => true,
                'query_var' => false,
                'rewrite' => false,
                'public' => false,
                'show_ui' => true,
                'show_admin_column' => true,
                'update_count_callback' => '_update_generic_term_count'
        ) );

        register_taxonomy( 'attachment_tag', 'attachment', array(
                'hierarchical' => false,
                'query_var' => false,
                'rewrite' => false,
                'public' => false,
                'show_ui' => true,
                'show_admin_column' => true,
                'update_count_callback' => '_update_generic_term_count'
        ) );

        register_taxonomy(
                'genre',
                array( 'attachment:audio' ), array(
                'labels' => array(
                        'name' => __( 'Genre' )
                ),
                'hierarchical' => false,
                'query_var' => false,
                'rewrite' => false,
                'public' => false,
                'show_ui' => true,
                'update_count_callback' => '_update_generic_term_count'
        ) );

        register_taxonomy(
                'year',
                array( 'attachment:video' ), array(
                'labels' => array(
                        'name' => __( 'Year' )
                ),
                'hierarchical' => false,
                'query_var' => false,
                'rewrite' => false,
                'public' => false,
                'show_ui' => true,
                'update_count_callback' => '_update_generic_term_count'
        ) );
}
add_action( 'init', 'ds_register_example_attachment_taxonomies' );