Summary (ideally in detail) of netcdf interfacing (i.e. save + load), analagous to the one on PP/FF

@trexfeathers suggested this can be a thin skeleton to start with
-- that gives us a place to put the awkward detail items (see below) without needing to provide a fully-fledged + rounded account from the first

See also this comment and subsequent ones ...

another case for the NetCDF I/O technical paper

I reckon we've now clocked up (at least) 4 "special detail issues" relating to netcdf, that would really like a place like that to live :

• deferred saving
• guess_axis
• chunking control
• split attributes

The tech papers probably shouldn't stay in the Developer's Guide really

Totally, I think they should all be combined in the further topics UserGuide area