Rock/soil zonations with overlapping domains will be assigned according to the last specification in the list of domains. To simplify the zonation of a problem with a dominant rock/soil type and isolated pockets or bands of another rock/soil type, the user should initially declare the dominant rock/soil type as covering the entire problem domain. With subsequent input lines, the user can overwrite the original rock/soil type for selected nodes with another rock/soil type. This layering approach is recommended and will often avoid leaving nodes of undeclared rock/soil types.