File format should be mandatory

[davidhassell]

No description provided.

[davidhassell]

Given that the format should be mandatory if the file variable exists, I think that it makes sense for all terms to be mandatory: location (already was), file, format, address. The only case when address could be omitted was if all of the data was undefined (e.g, an entire aggregated array of missing data), which is pretty unlikely.

Making all four terms mandatory is much cleaner, I think.