It's seems to be a regression to Note field in 3.3 instead of public and private Note introduced in 3.4 (and confirmed in the class -> Note / / deprecated)

use every where before SOCIETE_DONOTSEARCH_ANYWHERE was used

Conflicts:
	htdocs/contact/class/contact.class.php

everywhere

It's used to mark if the contact is gone or no(we can activate or desactivate the contact with this)
And if the contact is gone,we don't print her mail in the mail list,where we can send a mail