Emum solution for PHP

emun.php

   abstract class  OpServicesTypes {
        const NEWT = 'new';
        const RENEW = 'renew';
        const REPLACE = 'replace';
        const CHANGEADDRESS = 'change-of-address';
        const CHANGEOFNAME = 'change-of-name';
    }
    
    example: OpServicesTypes::NEWT