What is the restriction for using AS14 in a convertible vehicle?

The restriction for using AS14 in a convertible vehicle is that it is not allowed on the windshield. AS14 refers to a classification of window tinting that has specific limits on how much light can pass through the glass. Windshields are typically subject to stricter regulations to ensure driver visibility and safety, and applying AS14 tint to the windshield could reduce this visibility to an unsafe level.

It's important to note that while side and rear windows may have more leniency regarding tint darkness, the windshield serves as a critical point of visibility for the driver. Therefore, the regulations are designed to maintain road safety and allow for adequate visibility. In this context, the other options misinterpret the application of AS14 tint, suggesting broader permissions that do not align with safety regulations for windshield tinting.