DHARMA was brocasting the "numbers" from the radio tower for some yet unkown reason. After rewatching the S1 E2, I remembered that Rousseau changed the broadcast from the "numbers" to her distress call in 1988. This would mean that for about four years DHARMA didnot notice that they were no longer broadcasting the numbers. This is the same four year period that has a confict with Ben being with DHARMA or the hostiles. The date of the purge must be sometime before 1988. The only thing that gives us the date of the purge is Locke's dream. Any comments?