Revised code to also consider arg5...arg8 of input

src/main.cpp

@@ -167,12 +167,17 @@ namespace
 			//   ]
 			// }
 
-			// arg6: new attribute name
+			// Per the API, any of arg5 to arg8 is eligible to be the new attribute
+			// (depending on which one starts with "n:")
+			// However, only one will be considered (multiples will throw CAT_INVALID_ARGUMENT)
+			// Therefore, find the first one that starts with "n:"
+			const auto candidates = {input->arg5, input->arg6, input->arg7, input->arg8};
+			const auto mod_attr_ptr = std::find_if(std::begin(candidates), std::end(candidates), [](char* arg) {
+				return arg && boost::starts_with(arg, "n:");
+			});
 			const char* mod_attr_name = nullptr;
-			if (input->arg6) {
-				if (boost::starts_with(input->arg6, "n:")) {
-					mod_attr_name = input->arg6 + 2;
-				}
+			if (mod_attr_ptr != std::end(candidates)) {
+				mod_attr_name = (*mod_attr_ptr) + 2;
 			}
 			for (auto&& prefix : config->at("prefixes")) {
 				// If the metadata attribute starts with the prefix, then verify that the user