my %pattern_colvals;
    my %pattern_sizes;

    # convert pattern specs into internal representation

    while (<DATA>) {
        my ($pattern, $spec) = split /:\s*/, $_, 2;
        my @col_patterns = map [split /=/], split ' ', $spec;
        $pattern_sizes{$pattern} = @col_patterns;
        for (@col_patterns) {
            my ($col, $match_val) = @$_;
            push @{$pattern_colvals{$col}{$match_val}}, $pattern;
        }
    }