[Zope] how to presev information

[champier2002]

Hi,

I'm a new zope programmer.

I created a page which show different products (from a oracle 
database) which can be selected (products are shoiwn in checkbox 
format).

As I have a lot of product I also manage button ('Next' 
and 'previous')

The proble is : 
When I select some products from on page and then I use the 
button 'next' or 'pervious I lose the selected product of the last 
page..

Is someone can help me and give me some solution ??
Thanks for your help