Describe provision of sparse coordinates rather than for each data point

[erget]

As discussed at the meeting today and here, we could reduce the number of coordinates we encode for swath data where FOVs are distributed within FORs in a known way. I don't have time to do it right this second but I think it would be helpful to modify the warning note discussing this in the proposal, and to provide an example of how things are organised.

Some discussion will be needed on describing the geometry of the FOVs within the FOR, I'll defer that until later. For now I wanted to jot this down so that I don't forget it.

[ghost]

we could reduce the number of coordinates we encode for swath data where FOVs are distributed within FORs in a known way.

See Example 20 in the current version. It reduces the number of lat/lon coordinates by treating FORs as one entity. Is this what you meant?

[erget]

Quite right, I'd forgotten about that one. Basically, what I'd like to implement is a minor change to this note in order to match the outcome of our discussion at the meeting.

[ghost]

Alright. Once the relevant PR of the CF convention is accepted I will update (likely remove) that note.