These Drupal 6 panels files are included here as part of our Drupal source code examples project. (Please see that project page, including our promise to donate back to the Drupal open source community.)
This content is from the Drupal 6 panels project README file:
# $Id: README.txt,v 1.5 2008/07/15 23:59:36 merlinofchaos Exp $ Welcome to Panels 2. A little documentation should go here, but Panels 2 is a beast - you're best off checking the online handbook on Drupal.org, or the developer/API docs, which are available at http://doxy.samboyer.org/panels2/
These are direct links to the Drupal 6 panels project source code files included in this project: