What is the TID template Simplenews

Hello,

I use the simplenews for my newsletter and I want to know about what the tid of simplenews-body-newsletter - [tid]. tpl.php

Thank you

Example from page handbook Simplenews

For Drupal 6: In the simplenews module there are 4 tpl.php files available. One for the block, status, body and footer. The body and footer are the most important ones. They also allow you to style each newsletter in a completely different way. If you have a newsletter with tid 1126 then copy the body and footer tpl.php files and put them in your theme folder and rename them to: simplenews-newsletter-body--1126.tpl.php and simplenews-newsletter-footer--1126.tpl.php. With these you can style the body and footer of newsletter 1126