By default, the Drupal 6 trigger module displays appropriate actions for each trigger. Each action has declared which hooks it is appropriate for.
This module lifts that restriction, making any action available to any trigger. Use with care, as making an action assignment that does not make sense may lead to unintended consequences.
Note that because of its simplicity, and the fact that Drupal 5 does not recognize the "core = 6.x" statement in the .info file, and because triggerunlock does not actually declare its dependency on actions (since actions is built-in in Drupal 6), the 6.x version of triggerunlock can also be used by Drupal 5.