"Rule 6" is a joke amongst some divers - particularly those involved with GUE. Rule 6 says that "You must look good while doing it."
For example, showing up to the dive site in a new truck and wearing a sexy new drysuit and speeding around on a new X-scooter could be called "Rule 6 compliant." Doing the same but floating up feet first because you've never dived a drysuit before could be called a "Rule 6 violation."
"Rule 6" was borne of GUE/DIR, but truly hardcore divers might even use the term humorously outside of diving... For example, walking headfirst into a closed glass door could be called "Rule 6 noncompliant," and looking suave on a Saturday night while hanging out with the guys might be called "Rule 6 supercompliance."
For years, when asked why they dove with stainless steel D-rings and stainless steel bolt snaps rather than the cheaper but uglier brass alternatives, DIR guys would simply say, "Brass is a Rule 6 viloation."
It was a joke, caught by those who understood what "Rule 6" was.
The really funny part is that this implies that there's also Rule 1-5, and that there may even be more than just six rules. The truth was that there WERE no "rules" - it was made up to be funny. It could have easily been "Rule 42" or "Rule 18" as well.
Later, "Rule #1" was born, which was "Don't dive with [divers that have unsafe attitudes]," but "Rule #1" was never actually associated with "Rule 6."
By saying that your fins are "Rule 6 compliant," I'm saying (I guess in my own geeky, "groupspeak" kind of way) that they're very cool looking.
Nicely done! Did you put a cable or line through the center of the spring?