I had another look at some of the contracts' WHOIS provisions tonight, and stumbled over a point that I had missed earlier. In the Registrar Accreditation Agreement, the billing contact is not part of the published data set, but retained by the registrar; this does not prevent registrars from publishing that record. In most of the thick TLD agreements' appendices O (or, if sponsored, attachments 15; see .info for an unsponsored example), though, the billing contact is included in the published whois information. There is a similar (but better-known) inconsistency with the registrant's telephone and fax numbers and e-mail address which are, again, not part of the data set that must be published by registrars, but included with thick registry WHOIS elements.
For individual registrants, these data elements -- if entered as originally intended -- are among the most privacy-relevant ones in the entire WHOIS data set.
