The DET:OLD density conjecture for $C_4$-free cubic graphs

Let $G$ be a $C_4$-free cubic graph, and let DET:OLD$\%(G)$ denote the minimum density of an error-detecting open-locating-dominating set in $G$. DET:OLD density conjecture.

$$\textrm{DET:OLD}\%(G) \leq \frac{21}{22}.$$

The bound would improve the general upper bound DET:OLD$\%(G) \leq \frac{30}{31}$ for cubic graphs that permit DET:OLD, and is motivated by the extremal cubic graphs found on $16$ through $24$ vertices. Whether $\frac{21}{22}$ is the tight upper bound for all relevant cubic graphs remains open.