Revised comment.

io/teca_cf_layout_manager.cxx

@@ -449,18 +449,21 @@ int teca_cf_layout_manager::define(const teca_metadata &md_in,
 #endif
             )
 
-        // First implementation: Save the var to var_def so that attributes
-        // get written with other variables
-        // -> This caused an error when trying to write the attribute
-        //    "_FillValue" after writing the data.
+        // NOTE: The first implentation was the following:
+        // Save the var to var_def so that attributes get written with other variables
+        //
         // save the var id
         // this->var_def[coord_array_names[i]] = var_def_t(parent_id, var_id,
         //    var_type_code);
-
-        // Second implementation:
+        //
+        // While this approach avoided code duplication, it caused an error when
+        // trying to write the attribute "_FillValue" after writing the data.
+        // To work around this error, we write the attributes of the coordinate
+        // axes directly here instead of saving the var id for later writing.
+ .      //
         // write variable attributes
-        // this needs to be done before writing arrays to avoid a NetCDF error
-        // of specifying fill value when data already exists.
+        // (this needs to be done before writing arrays to avoid a NetCDF error
+        // of specifying fill value when data already exists)
         teca_metadata array_atts;
         if (array_attributes.get(coord_array_names[i], array_atts) == 0)
         {