WordPress at a glance
function is not described

_get_additional_user_keys() WP 3.3.0

Returns a list of meta keys to be (maybe) populated in wp_update_user().

The list of keys returned via this function are dependent on the presence of those keys in the user meta data to be set.

No Hooks.

Return

Array. List of user keys to be populated in wp_update_user().

Usage

_get_additional_user_keys( $user );
$user(WP_User) (required)
WP_User instance.

Code of get additional user keys: wp-includes/user.php VER 5.0.3

<?php
function _get_additional_user_keys( $user ) {
	$keys = array( 'first_name', 'last_name', 'nickname', 'description', 'rich_editing', 'syntax_highlighting', 'comment_shortcuts', 'admin_color', 'use_ssl', 'show_admin_bar_front', 'locale' );
	return array_merge( $keys, array_keys( wp_get_user_contact_methods( $user ) ) );
}