HTML 4.01: "Calculating the width of columns", first example

Hello,

I'm seeking help in understanding the text accompanying the first =
example in HTML 4.01, Tables, Calculating the width of columns.

http://www.w3.org/TR/html4/struct/tables.html#h-11.2.4.4

The text says:

--quote--
[...]
The table in this example contains six columns. The first one does not =
belong to an explicit column group. The next three belong to the first =
explicit column group and the last two belong to the second explicit =
column group. [...]
--quote--

The example this text refers to reads:

--html--
<TABLE>
<COLGROUP>
   <COL width=3D"30">
<COLGROUP>
   <COL width=3D"30">
   <COL width=3D"0*">
   <COL width=3D"2*">
<COLGROUP align=3D"center">
   <COL width=3D"1*">
   <COL width=3D"3*" align=3D"char" char=3D":">
<THEAD>
<TR><TD>=20
...
...rows...

</TABLE>
--html--

Why does the first column of this table not belong to an explicit column =
group? It is a child of a <COLGROUP> element and therefore I'd consider =
it part of an explicit column group. Isn't this the case?

(The errata do not have an entry concerning this issue.)

-kris=