[CF-metadata] regions

[Jonathan Gregory]

Dear Karl

> Is there a CF-compliant way to combine official regions (e.g., a region 
> that includes both North America and South America)?

I don't think so. We can either invent one, or introduce additional names for
combined regions. I would prefer the latter, as it involves no new machinery,
if it's practical. I think it would work if the combined regions requiring
names are a finite set, which I guess would be the case e.g. I suspect you will
not want a region name for Afghanistan plus Zimbabwe.

Best wishes

Jonathan