mention the .URL macro more verbosely, as per patch from

Martin Schulze <joey@infodrom.org>
Branden Robinson <branden@debian.org> 
Colin Watson <cjwatson@debian.org>

man7/man.7

@@ -457,7 +457,9 @@ its results are like those of the
 .B \&.IP
 command.
 .SS "Hypertext Link Macros"
-(Feature supported with groff only.)
+(Feature supported with
+.B groff
+only.)
 In order to use hypertext link macros, it is necessary to load the
 .B www.tmac
 macro package.
@@ -483,6 +485,48 @@ This and other related macros are new, and
 many tools won't do anything with them, but
 since many tools (including troff) will simply ignore undefined macros
 (or at worst insert their text) these are safe to insert.
+.\" The following is a kludge to get a paragraph into the listing.
+.TP
+.B " "
+It can be useful to define your own
+.B URL
+macro in manual pages for the benefit of those viewing it with a roff
+viewer other than
+.BR groff .
+That way, the URL, link text, and trailer text (if any) are still visible.
+.\" The following is a kludge to get a paragraph into the listing.
+.TP
+.B " "
+Here's an example:
+.RS 1.5i
+\&.de URL
+.br
+\\\\$2 \\(laURL: \\\\$1 \\(ra\\\\$3
+.br
+\&..
+.br
+\&.if \\n[.g] .mso www.tmac
+.br
+\&.TH
+.I ...
+.br
+.I (later in the page)
+.br
+This software comes from the
+.br
+\&.URL "http://www.gnu.org/" "GNU Project" " of the"
+.br
+\&.URL "http://www.fsf.org/" "Free Software Foundation" .
+.RE
+.\" The following is a kludge to get a paragraph into the listing.
+.TP
+.B " "
+In the above, if
+.B groff
+is being used, the
+.B www.tmac
+macro package's definition of the URL macro will supersede the locally
+defined one.
 .PP
 A number of other link macros are available.  See
 .BR groff_www (7)