librenms-librenms/includes/discovery/os/multimatic.inc.php

<?php

if (!$os) {
    if (preg_match('/^CS121/', $sysDescr)) {
        if (strstr(snmp_get($device, 'UPS-MIB::upsIdentManufacturer.0', '-Oqv', ''), 'Multimatic')) {
            $os = 'multimatic';
        }
    }
}