Merge branch '9-update-manual-after-removal-key_netcdf4' into 'main'

Resolve "Update manual after removal key_netcdf4"

Closes #9

See merge request !17

latex/NEMO/subfiles/chap_DIA.tex

@@ -1421,11 +1421,12 @@ It is unclear how XIOS decides on suitable chunking parameters before applying c
 be necessary to rechunk data whilst combining multiple\_file output. \forcode{REBUILD_NEMO} is capable
 of doing this.
 
-\section[NetCDF4 support (\texttt{\textbf{key\_netcdf4}})]{NetCDF4 support (\protect\key{netcdf4})}
+\section[NetCDF4 support]{NetCDF4 support}
 \label{sec:DIA_nc4}
 
-Since version 3.3, support for NetCDF4 chunking and (loss-less) compression has been
-included.  These options build on the standard NetCDF output and allow the user control
+Since version 5.0, only NetCDF4 (version 4.1 onwards, recommended) built with HDF5 (version 1.8.4
+onwards, recommended) is supported. This allows chunking and (loss-less) compression.
+  These options are built on the standard NetCDF output and allow the user control
 over the size of the chunks via namelist settings.  Chunking and compression can lead to
 significant reductions in file sizes for a small runtime overhead.  For a fuller
 discussion on chunking and other performance issues the reader is referred to the NetCDF4
@@ -1437,9 +1438,7 @@ files and mean files produced via the old IOIPSL interface when \key{xios} is no
 used. As such it has limited use since chunking and compression can be applied at the
 rebuilding phase of such output.
 
-The features are only available when the code has been linked with a NetCDF4 library
-(version 4.1 onwards, recommended) which has been built with HDF5 support (version 1.8.4
-onwards, recommended).  Datasets created with chunking and compression are not backwards
+Datasets created with chunking and compression are not backwards
 compatible with NetCDF3 "classic" format but most analysis codes can be relinked simply
 with the new libraries and will then read both NetCDF3 and NetCDF4 files.  \NEMO\
 executables linked with NetCDF4 libraries can be made to produce NetCDF3 files by setting
@@ -1451,19 +1450,7 @@ the \np{ln_nc4zip}{ln\_nc4zip} logical to false in the \nam{nc4}{nc4} namelist:
   \label{lst:namnc4}
 \end{listing}
 
-If \key{netcdf4} has not been defined, these namelist parameters are not read.  In this
-case, \np{ln_nc4zip}{ln\_nc4zip} is set false and dummy routines for a few
-NetCDF4-specific functions are defined.  These functions will not be used but need to be
-included so that compilation is possible with NetCDF3 libraries.
-
-When using NetCDF4 libraries, \key{netcdf4} should be defined even if the intention is to
-create only NetCDF3-compatible files.  This is necessary to avoid duplication between the
-dummy routines and the actual routines present in the library.  Most compilers will fail
-at compile time when faced with such duplication.  Thus when linking with NetCDF4
-libraries the user must define \key{netcdf4} and control the type of NetCDF file produced
-via the namelist parameter.
-
-Chunking and compression is applied only to 4D fields and there is no advantage in
+Chunking and compression are applied only to 4D fields and there is no advantage in
 chunking across more than one time dimension since previously written chunks would have to
 be read back and decompressed before being added to.  Therefore, user control over chunk
 sizes is provided only for the three space dimensions.  The user sets an approximate