This map drawn over a photograph shows the results of a land capability survey. Each area has a land resource inventory code or equation. Above the equation line, the first letters define the parent rock type (for example Gw is greywacke rock). The second number defines the soil type, and the next letter is the slope (A for flat, F for steep). Below the equation line, the first group of letters defines the type and severity of erosion. The second group defines the vegetation cover. The next set of letters (for instance Vle 29) define the land capability class (I–VIII), followed by the dominant limitation to agricultural use (e is erosion, w is wetness or flooding, s is soil and cl is climate).