Specifies a file which receives a dump of the set of
positions matched by the matching process. The file is
formatted like a sextractor output file, with
five columns, containing (1) running object number, (2 and
3) RA and Dec of the source on the sky, and (4 and 5)
x and y positions of the source on the
CCD.
Type: string; default: absent -- no file written by default