Add documentation links.

Author: pp-mo

docs/src/further_topics/netcdf_io.rst

@@ -189,6 +189,17 @@ Deferred Saving
 TBC
 
 
+Dataless Cubes
+--------------
+It now possible to have "dataless" cubes, where ``cube.data is None``.
+When these are saved to a NetCDF file interface, this results in a netcdf file variable
+with all-unwritten data (meaning that it takes up no storage space).
+
+In order to load such variables back correctly, we also add an extra
+``iris_dataless_cube = "true"`` attribute : this tells the loader to skip array creation
+when loading back in, so that the read-back cube is also dataless.
+
+
 Guessing Coordinate Axes
 ------------------------
 

docs/src/whatsnew/latest.rst

@@ -40,6 +40,9 @@ This document explains the changes made to Iris for this release
    :func:`~iris.fileformats.netcdf.saver.save_mesh` also supports ``zlib``
    compression. (:issue:`6565`, :pull:`6728`)
 
+#. `@pp-mo`_ made it possible to save 'dataless' cubes to a netcdf file, and load them
+   back again. (:issue:`6727`, :pull:`6739`)
+
 
 🐛 Bugs Fixed
 =============