What is the 15-3 rule?

Excuse me, could you elaborate on the so-called 15-3 rule in the context of cryptocurrency or finance? I'm not familiar with this term and I'm curious to understand its significance and how it might be applied in this industry. Is it a risk management strategy, a trading principle, or something else entirely? I'd appreciate it if you could provide a concise explanation and any relevant examples to help me grasp the concept better.