Create Model with command line

Hi..
I created model from command line and when i open the model file to edit there is this part which i don't understand.

PHP Code:

protected $cleanValidationRules = true; 


Can anyone give explanation or point out the documentation on what is it and how to use that part?
I've tried search on the userguide but found nothing, or maybe i wasn't looking carefully because i only use the search input with cleanValidationRules text.