thumbLabel<N>
This parameter specifies a different label for each thumbnail; thumbLabel1 for thumbnail 1, thumbLabel2 for thumbnail 2, and so on.
The text appears in the lower right corner of each corresponding thumbnail.
Example
<param name="thumbLabel1" value="My first page" />
<param name="thumbLabel2" value="My second page" />
<param name="thumbLabel3" value="My third page" />