Clameurs/sites/all/modules/contrib/admin/workflow/workflow_rules/workflow_rules.module

<?php
/**
 * @file
 * Provide rules for workflows.
 * Why it's own module? Some sites prefer rules, some prefer actions,
 * all prefer a lower code footprint and better performance.
 * Additional creadit to gcassie ( http://drupal.org/user/80260 ) for
 * the initial push to split rules out of core workflow.
 */


/**
 * Implements hook_workflow().
 *
 * @param $op
 *   The current workflow operation: 'transition pre' or 'transition post'.
 * @param $old_state
 *   The state ID of the current state.
 * @param  $new_state
 *   The state ID of the new state.
 * @param $node
 *   The node whose workflow state is changing.
 */
function workflow_rules_workflow($op, $old_state, $new_state, $node) {
  switch ($op) {
    case 'transition post':
      // Rules are updated on after the transition.
      if ($old_state == $new_state) {
        rules_invoke_event('workflow_comment_added', $node, $old_state, $new_state);
        return;
      }
      rules_invoke_event('workflow_state_changed', $node);
    break;
  }
}