What resets the 7 year clock??

[arejay]

I have spent hours reading everything I possibly could on this forum, very, very good information. I can not even begin to thank all that contribute, great site!!!

In my reading I have not come across an answer to the following:

Credit reporting drops off every 7 years correct? If so, what is the start date of this time period? The day it is charged off, the day you settle, etc.? Also, after this clock starts, what will reset it? I ask this because if an account is near the "7 year drop off date" and a dispute or validation letter resets the clock, it obviously wouldnt be wise to send those letters.

If possible and if it doesnt already exist, can someone post the things that reset this clock and also what starts it in the first place. Thanks!!!