User must change password after reset?

I am looking at the password policy settings and am wondering what "User must change password after reset?actually does. I turned it on. I tried changing some passwords in an ldap client and didnt get any messages or errors after authn again. And I didnt see a special attribute in the persons entry. Any clues?

[318 byte] By [Xoth] at [2007-11-26 7:52:22]