@cpelley I disagree with your suggestion above. If you allow ```degree``` to be also associated with rotated pole data, then there would be no way in which to determine whether the data represented in NetCDF is indeed rotated pole, particularly if no explicit coordinate system is specified and the user has given the coordinate name of ```latitude``` or ```longitude``` instead of ```grid_latitude``` or ```grid_longitude```.

Your concerns are valid, but I think that they more lie with failures within the CF specification and its marriage with the CF standard name table. I don't see it as a blocker to this PR.

Iris currently outputs the units of both lat/lon coordinate and rotated pole coordinate data to NetCDF as ```degrees```. We don't discriminate between ```degree_north```, ```degree_east``` and ```degrees```. Perhaps we should, perhaps we shouldn't ... that's a separate discussion (IMHO).

The simple fact is that if we load NetCDF **circular** longitude data, then save this cube to NetCDF, then read it back into Iris, the longitude coordinate is not longer circular. This is simply due to the fact that we've explicitly chosen to represent ```degree_east``` as ```degrees``` ... something's gotta give here, and I'm suggesting this one line change.

So unless you disagree (or anyone else does) with the premise of this PR ... it's :+1: good to go as far as I'm concerned.