[aprssig] Filter to obtain specific stations in a region

[Bill Vodall]

I'm experimenting...

Is there a way to use the javAPRSfilters to extract only
the symbols in a region?

I can get the region:  a/57/-125/41/-104   (NWAPRS)

I can get the symbols:   s//a/W   (all the winlink stations)

When I put the two together, it's an OR operation, not
an AND.   So I get everything for the region AND all the
Winlink stations.

I've played a bit with the negation operator to no success.

This isn't hard with an external filter, I'm just curious
if it can be done with the tools at hand.

Thanks,
Bill - WA7NWP