I also added the -false primary as found with findutils's find(1).

Using my -fprint on findutils or my hacked NetBSD find(1) does not do what 
I wanted. For example, if saving results of all files that start with a 
vowel or saving results of all files owned by group operator, then the 
list of files owned by group operator would not include the files starting 
with a vowel.

findutils's find has a workaround for this with -false.

Here is my manpage addition:

-false  This primary always evaluates to false.  This can be used follow-
         ing a primary that caused the expression to be true to make the
         expression to be false.  This can be useful after using a -fprint
         primary so it can continue to the next expression (using an -or
         operator, for example).

And:

find  /  \(  -newer  ttt  -fprint ~/newer-file  -false  \)  -o \

       \(  -user wnj  -fprint ~/wnj-file  \)
       The list of files that are newer than ``ttt'' are saved to a file
       named ``~/newer-file''; and the list of files owned by ``wnj'' are
       saved to a file named ``~/wnj-file''.  The -false primary is
       important so that the ``~/wnj-file'' results file will also con-
       tain the list of files newer than ``ttt''.

The alternative is to have -fprint always return false, which may not be 
expected behaviour and is different from findutils.

  Jeremy C. Reed

p.s. How can I get the formatting correct with mdoc for above example?

I have:

.It Li "find  /  \e(  -newer  ttt  -fprint ~/newer-file  -false  \e)  -o \e"
.It Li "   \e(  -user wnj  -fprint ~/wnj-file  \e)"
The list of files that are newer than

How can I improve the above?

Should I just put the entire long find command on one line and let the 
reader figure it out?