From the release notes for htdig-3.0b5:
* htsearch got a new option '-r' which will allow
it to produce raw output. This output can easily parsed
by a wrapper program to produce custom HTML or other
output for the search results.
The original changelog noted that the format produced
by the -r option was in the documentation, but I can't
find any trace of it.
Has this feature perhaps been removed? A quick search
in htsearch.cc didn't turn up an 'r' command line option.