my $re_str=qr{([0-6BS])};
$_="B";
my $ans;
if (eval m{$re_str})

##</code><code>##

my $re_str="qr{(&#91;0-6BS&#93;)}";
$_="B";
my $ans;
if (eval m{$re_str})

##</code><code>##

#not tested, YMMV
for $key (keys %options)
{
    if ($key =~ s/^#//)
    {
        if (/$key/)
        {
            print "Match: $1\n";
        }
    }
    else
    }
        if ($_ eq $key)
        {
            print "Equals: $1\n";
        }
    }
}