Make EM attributes accessible

aa.php

register_meta('post', '_location_name', 'custom_sanitize_as_is', 'custom_auth_always_allow');
register_meta('post', '_event_name', 'custom_sanitize_as_is', 'custom_auth_always_allow');

function custom_sanitize_as_is( $meta_value, $meta_key, $meta_type ) {
	return $meta_value;
}

function custom_auth_always_allow( $allowed, $meta_key, $post_id, $user_id, $cap, $caps ) {
	return true;
}