Which contraction is used by automated stations to indicate no layers detected at or below 12,000 feet AGL?

The contraction utilized by automated stations to indicate that there are no layers detected at or below 12,000 feet Above Ground Level (AGL) is "CLR." This term is a common abbreviation in meteorological communications, conveying that the sky is clear of any significant obstructions or cloud layers within the specified altitude. When the automated weather data reflects that there are no clouds or layers present in that altitude range, "CLR" succinctly communicates this status to pilots and air traffic control, ensuring they are informed of optimal flying conditions and can make decisions based on clear airspace.

While other terms like SKC (sky clear) may also suggest good visibility and clear skies, "CLR" is specifically tied to the absence of layers, making it the most appropriate choice in this context for denoting conditions below that flight level. "NO LYR" may seem like a fitting alternative, but it is not the recognized contraction for such reports, and "N/A" (not applicable) does not convey the weather information required in this scenario.