The Princeton University Host Database has been modified to retire the WELL-KNOWN-SERVICES field.
At one time, the contents of this field determined the DNS WKS resource record. That resource record has not been in-use for many years.
At one time, the contents of this field helped determine if a Host Database entry was eligible for OIT DHCP and BootP Services. The field stopped playing this role on October 7 2003.
The field no longer served any function, so it has been retired.