In rev 1.61, references to resolv.conf.tail were removed, so it appears that this page is now meant to solely document resolv.conf, a single file. So that makes this sentence make not-so-much sense:
The configuration options (which may be placed in either file) are: Diff below removes the "either file" wording. Cheers, Scott diff c90212a02b599071a4e7b5e4709b67a0988d81b7 /usr/src blob - 49ee20b2a5c863735baedf6c938512c029e76903 file + share/man/man5/resolv.conf.5 --- share/man/man5/resolv.conf.5 +++ share/man/man5/resolv.conf.5 @@ -69,11 +69,11 @@ or semicolon .Pq \&; in the file indicates the beginning of a comment; subsequent characters up to the end of the line are not interpreted by the routines that read the file. .Pp -The configuration options (which may be placed in either file) are: +The configuration options are: .Bl -tag -width nameserver .It Ic nameserver IPv4 address (in dot notation) or IPv6 address (in hex-and-colon notation) of a name server that the resolver should query.