# start an attempt at determining whether this string might be a callsign
sub iscallsign
{
- my $call = shift;
- return 1 if $call =~ /^\w+\d+/;
- return 1 if $call =~ /^\d+\w+/;
+ my $call = uc shift;
+ return 1 if $call =~ /^[A-Z]+\d+[A-Z]+/;
+ return 1 if $call =~ /^\d+[A-Z]\d+[A-Z]+/;
return undef;
}