Document the new `ignore_axis` functionality.

[HGWright]

📚 Documentation

#5003 requested and #5551 delivered the ability to manually set ignore_axis for a coordinate and as a result guess_coord_axis will not act on that coordinate. We currently do not have documentation for this change as we didn't feel the need to require it in #5551. This is something we would like to add in the future. The docstrings have been updated but we feel that this deserves a bit more documentation.

[trexfeathers]

This is another case for the NetCDF I/O technical paper*. Introducing this paper does NOT mean writing the whole thing - the plan would be to just add the relevant section, and make it clear to readers that the page is not exhaustive and there is more to write in future.

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

[pp-mo]

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

[trexfeathers]

@ESadek-MO is laying the ground work in #5597, simply because this is the first one to be worked on

[trexfeathers]

@ESadek-MO is laying the ground work in #5597, simply because this is the first one to be worked on

✅

iris/docs/src/further_topics/netcdf_io.rst

Lines 27 to 36 in 5e00971

	=============================
	NetCDF I/O Handling in Iris
	=============================
	This document provides a basic account of how Iris loads and saves NetCDF files.
	.. admonition:: Under Construction
	This document is still a work in progress, so might include blank or unfinished sections,
	watch this space!