my $TGROUP = { 
     COLS    => 4,
     COLSPEC => [... Array of hashes...],
     TBODY   => HASH(0x8b...),
     THEAD   => HASH(0x8bc...)
}

##</code><code>##

<TRGROUP...
  <COLS ...
  <COLSPEC ..
  <TBODY ....
  <THEAD ...
>

##</code><code>##

<TRGROUP...
  <COLS ...
  <COLSPEC ..
  <THEAD ....
  <TBODY ...
>

##</code><code>##

 my $TGROUP = { 
     COLS    => 4,
     COLSPEC => [... Array of hashes...],
     THEAD   => HASH(0x8b...),
     TBODY   => HASH(0x8bc...)
}