When using this function it helps to think of the return value as a number within a range rather than a constant value. To clarify, if I wanted something to happen when my PC was standing on a particular type of terrain using this: object oPC = OBJECT_SELF; int nDirt = GetSurfaceMaterialsAtLocation(GetLocation(oPC)); if (nDirt == SM_TYPE_DIRT) { DoThis(); } object oPC = OBJECT_SELF; int nTerrain = GetSurfaceMaterialsAtLocation(GetLocation(oPC)); if ((nTerrain >= SM_TYPE_DIRT) && (nTerrain < SM_TYPE_GRASS)) { DoThat(); } * Added in Patch 1.23