This is a script that can be used to insert fields into an existing Enzo dataset. For an example of how to run, see the end of the insert_fields.py file. Alternatively, you can do, assuming insert_fields.py is in your Python path: from insert_fields.py import * fields_to_add =  fields_to_add.append(NewField('Mach',63)) fields_to_add.append(NewField('PreShockTemperature',64)) fields_to_add.append(NewField('PreShockDensity',65)) bdict = add_field('DD1701', fields_to_add) This must be run in the dataset directory where the parameter file 'DD1701' and all of its data resides. I strongly suggest you backup your dataset before using this. It has not yet been tested with a variety of precision settings.