//status: edited

A basic logging facility in _WSJT-X_ saves QSO information to files
named `wsjtx.log` (in comma-separated text format) and `wsjtx_log.adi`
(in standard ADIF format).  These files can be imported directly into
other programs (such as spreadsheets and popular logging programs).
As described in the <<INSTALL,Installation>> and <<PLATFORM,Platform
Dependencies>> sections, different operating systems may place your
local log files in different locations.  You can always navigate to
them directly by selecting *Open log directory* from the *File* menu.

More elaborate logging capabilities are supported by third party
applications like {jtalert}, which can log QSOs automatically to other
applications including {hrd}, {dxlsuite}, and {log4om}.  

The program option *Show DXCC entity and worked before status*
(selectable on the *File | Settings | General* tab) is intended mostly for
use on non-Windows platforms, where {jtalert} is not available.  When
this option is checked, _WSJT-X_ appends some additional information to
all CQ messages displayed in the _Band Activity_ window.  The name of
the DXCC entity is shown, abbreviated if necessary.  Your "`worked
before`" status for this callsign (according to log file
`wsjtx_log.adi`) is indicated by highlighting colors, if that option
is selected.

_WSJT-X_ includes a built-in `cty.dat` file containing DXCC prefix
information.  Updated files can be downloaded from the {cty_dat} web
site when required.  If an updated and readable `cty.dat` file is
present in the logs folder, it is used in preference to the
built-in file.

The log file `wsjtx_log.adi` is updated whenever you log a QSO from
_WSJT-X_.  (Keep in mind that if you erase this file, you lose all
"`worked before`" information.)  You can append or overwrite the
`wsjtx_log.adi` file by exporting your QSO history as an ADIF file
from another logging program.  Turning *Show DXCC entity and worked
before status* off and then on again causes _WSJT-X_ to re-read
the log file.  Very large log files may cause _WSJT-X_ to slow down
when searching for calls.  If the ADIF log file has been changed
outside of _WSJT-X_ you can force _WSJT-X_ to reload the file from the
*Settings | Colors* tab using the *Rescan ADIF Log* button, see
<<COLORS,Decode Highlighting>>.

Additional features are provided for *Contest* and *Fox* logging.
(more to come, here ...)
