my @ef = (extract_multiple($param_string,
                             [
                               sub { extract_delimited($_[0]) },
                               sub { extract_bracketed($_[0]) },
                               sub { extract_variable($_[0]) },
                             ],
                              undef,0));

    my ($extracted, @fields, $field, @subfields);

    foreach $extracted (@ef) {
      if ($extracted ne ",") {
        if ($extracted =~ /^["'`\[\(\$\@\%]/ ) {
          push(@fields, $extracted);
        } else {
            # If this is not the first field, remove any leading
            # spaces and a comma. If it was the very first field,
            # then the first comma is significant.
          if (@fields) {
            ($extracted) = ($extracted =~ /\s*,?(.*)/);
          }
          @subfields = split(/,/, $extracted);  # Split on comma
          foreach $field (@subfields) {
            ($field) = ($field =~ /([^\s]+)/);  # Keep non-space
            push(@fields, $field);
          }
        }
      }
    }