Notices in X-Cart 4's var/log folder bloat the logs unnecessarily. I tried turning them off in the config.php, in .htaccess, and even at the entire server level, and x-cart kept logging them.
Drove me nuts.
The solution is as follows:
* Error handler
function func_error_handler($errno, $errstr, $errfile, $errline)
// SD - Don't Log Notices
if (in_array($errno, array(1, 3, 8, 9, 10)))
// / SD - Don't Log Notices