You know, I found that link by reading the 5250 help at WRKSYSVAL QPWDLVL.
See the System i Security Reference, SC41-5302
publication for additional considerations prior to
changing the password level to 3. Moving from QPWDLVL 3
back to 0 is not allowed.
Then I googled that, System i Security Reference
Then I weeded that down to 7.1.
Took some research...