DHCP option 60 is a client option (extension). When requesting an IP address from a DHCP server, with this option the client provides the vendor class identifier.
Need this because my inet provider (UPC / Inode) only assigns me an ip address in the VOIP subnet if the dhcp client identifies as "AVM DHCPC" (FritzBox).
By the way to be more precise: Is it possible to define a virtual interface which uses that dhcp client option 60?
They do not. This is a User BB, and no Sophos Employees are paid to be here except in the beta forums where the developers come to look at any issues with their new code.