BUG: Dumping to multiple files failed with an error message complaining about a missing 'append yes' option.

src/USER-NETCDF/dump_netcdf.cpp

@@ -343,7 +343,7 @@ void DumpNetCDF::openfile()
       if (framei <= 0) framei = nframes+framei+1;
       if (framei < 1)  framei = 1;
     } else {
-      if (framei != 0)
+      if (framei != 0 && !multifile)
         error->all(FLERR,"at keyword requires use of 'append yes'");
 
       int dims[NC_MAX_VAR_DIMS];