[CF-metadata] X and Y projection coordinate (center vs corner)

[Jonathan Gregory]

Dear all

In view of our general agreement, I have just proposed to add some text to
the CF standard in ticket 44. I've proposed this as a defect, because it
doesn't change the standard, just clarifies it. Please have a look. If anyone
objects, it can't be accepted as a defect, but if you think it's OK but that
the wording should be improved, that's fine - please make suggestions in the
ticket.

Cheers

Jonathan