[Zope] Newbie: Confusion at sequence-odd, sequence-even and sequence-start

[Alfredo P. Ricafort]

Hi,

I have this code that display images in a 2-column table.  The idea is
for <dtml-in> to loop inside a folder containing these images.  When the
counter is odd, an opening <tr> will be inserted; and when a the counter
is even a closing </tr> is inserted as well.  

 ---------------------
|  Image 1 | Image 2  |
 ---------------------
|  Image 3 | Image 4  |
 ---------------------

The code is like this:

<table width=100% border=1>
<dtml-in objectValues>

   <dtml-if sequence-odd>          # Check if the sequence no. is even
     <tr>                            and create a row.
   </dtml-if>

    <td>                           # Create a column and
       <dtml-var sequence-number>    insert the image or text
    </td>

   <dtml-if sequence-even>         # Close the table if even
      </tr> 
   </dtml-if>

   </dtml-in> 
</table> 

When I ran this code, I noticed that in the first iteration, when the
sequence-number is 1, the condition <dtml-if sequence-odd> is not
satisfied while the <dtml-if sequence-even> is! So the first few lines
of the generated HTML would appear like this. Notice that the 1 column
(<td></td>) is created first before the row.

<table width=100% border=1>

    <td> 
       1
    </td>

    </tr>         #
 
    <tr> 
     :
     :

So, could somebody explain to me what is going on here.  Why can't Zope
recognize the first iteration as an odd number, when the value of the
sequence-number  is 1.  And why is the statement <dtml-if sequence-even>
is satisfied at this point?

Thanks.

AL