General developer forum

I have noticed some errors when restoring logs. I checked the source code of the forum module and found these calls to logging function in mod/forum/lib.php:

add_to_log($course->id, 'forum', 'mail error', "discuss.php?d=$discussion->id#$post->id", substr($post->subject,0,30), $cm->id, $userto->id);

and others with the third parameter:
mail blocked
mail digest error
mail digest blocked

But these log actions are not defined in table mdl_log_display, is this a bug? I thought that each action must be defined in this table...

skodak