$subj = "<u\nid=u>$subj</u>" if $root_anchor eq $id_m;
$rv .= $subj . "\n";
$rv .= _th_index_lite($mid_raw, \$irt, $id, $ctx);
my @tocc;
foreach my $f (qw(To Cc)) {
$subj = "<u\nid=u>$subj</u>" if $root_anchor eq $id_m;
$rv .= $subj . "\n";
$rv .= _th_index_lite($mid_raw, \$irt, $id, $ctx);
my @tocc;
foreach my $f (qw(To Cc)) {