Shows all available informations about callsign. You can only look at it or see why the QSO Check wrote warning.
On the first line are basic informations - call, locator and time to easy WAV record of QSO.
Known call from unknown locator means that DF7DJ is known call but was worked on the past from unknown locators. Locator would be wrong.
Follows informations from C_W database for call and call with appended or stripped /P or /number.
Name is informational, known name means that call is probably correct.
Other possible texts:
Callsign unknown in namedb and C_W - unknown call. Check if callsign is correct.
Crossmode QSO ? - Crossmode should be valid of course but sometimes one of station forgot to switch log and enter different report than send.
Unknown DXCC prefix - Typo in callsign or new DXCC and obsolete cty.dat.
Prefix and big wwl don't match - Probably typo in locator (JO69UN for OK). In case of disputable location look at http://f6fvy.free.fr/qthLocator/fullScreen.php
Call is with(out) /P and in C_W exists call with(out) /P (or /number) - In C_W database are both variants of call. Maybe you have wrong /x. Beware of I and OE station. It call also happen if you have in C_W entries from old ages when stations had to give /P in contests. Recommended way is to remove confusing items from C_W.
Other similar call known from this locator. Maybe XXyXXX ? - In C_W is known similar call from same locator. Maybe typo in callsign?
Locator on band X is YYYYYY - call is worked also on other band but from other locator
Call on band X is YYYYYY - call is worked also on other band but differs in /x or CEPT prefix.