document CATO and handle a parameter of -1 correctly
document CATO and handle a parameter of -1 correctly

crystalline/openc2e,bdonlan/openc2e,crystalline/openc2e,ccdevnet/openc2e,bdonlan/openc2e,crystalline/openc2e,ccdevnet/openc2e,ccdevnet/openc2e,ccdevnet/openc2e,bdonlan/openc2e,bdonlan/openc2e,ccdevnet/openc2e,crystalline/openc2e,crystalline/openc2e,ccdevnet/openc2e