+ AA6YQ comments below
The current CWops roster has just under 2500 calls, although a few of them are duplicates as some members have more than one call.
+ Thanks. I suspect that's too many for a simple filter like
(MODE='CW') and (CALLSIGN in ('VK9NS', 'OH2BH','P5DX', ....))
+ which you would edit each time you log a QSO with a CWOPs member.