The Shields Rating System

A number of articles include a Shields rating - from 0 to 5.

Shields
0 Shields Not secure, or does not apply.
1 Shield No programming required to break this security, and/or security through obscurity.
2 Shields Needs a little more effort or knowledge - but readily available via research.
3 Shields Moderate effort to break security, or may have known issues that can be patched.
4 Shields Pretty good. Would require a great deal of knowledge/effort to break security.
5 Shields As secure as it can be. Nothing is impenetrable, but this is the state-of-the-art for this context.