@Greg-Plamondon
They talk about that here: https://wiki.fogproject.org/wiki/index.php?title=BIOS_and_UEFI_Co-Existence#Building_custom_DHCP_Classes_for_co-existence_with_FOG
Basically, it means start at character 0 and go 20 characters after that, then compare what you see in those 20 characters to the following string.