--dhcp-match=set:<tag>,<option number>|option:<option name>|vi-encap:<enterprise>[,<value>]
Without <value>, set <tag> if the client sends a DHCP option of the given number or name. With <value>, set <tag> only if the client sends the option matching or containing <value>.

The value may be of the form "01:ff:*:02" in which case the value must match (apart from wildcards) but the option sent may have unmatched data past the end of the value. The value may also be of the same form as in --dhcp-option in which case the option sent is treated as an array, and one element must match. --dhcp-match=set:efi-ia32,option:client-arch,6 sets the tag efi-ia32 if the number 6 appears in the list of architectures sent by the client in option 93. (See RFC 4578 for details.) If the value is a string, substring matching is used.

The special form with vi-encap:<enterprise number> matches against vendor-identifying vendor classes for the specified enterprise. Please see RFC 3925 for more details of these rare and interesting beasts.