(documentationslopeGradientEnglishLanguage "(slopeGradient ?AREA ?SLOPE) means that in the LandArea ?AREA there is an incline of ?slope, where ?SLOPE is the percent of vertical rise over horizontal distance. slopeGradient gives an approximate value for nonzero slope over ?AREA, without regard to orientation. For example, (slopeGradient ?AREA 0.10) means that there is a 10% incline across the area, without specifying the orientation in which the land rises or falls. Also see slopeGradientTowardsOrientation.")