diff --git a/Changelog.rst b/Changelog.rst
index cc4bfd912..3eba038bb 100644
--- a/Changelog.rst
+++ b/Changelog.rst
@@ -1,3 +1,13 @@
+Version NEXTVERSION
+----------------
+
+**2026-??-??**
+
+* Support for HEALPix grids
+  (https://github.com/NCAS-CMS/cfdm/issues/370)
+
+----
+
 Version 1.13.0.0
 ----------------
 
diff --git a/README.md b/README.md
index e9d4af6a4..1f22fa988 100644
--- a/README.md
+++ b/README.md
@@ -87,6 +87,7 @@ The ``cfdm`` package can:
 * write and append field and domain constructs to netCDF and Zarr v3
   datasets on disk,
 * read, write, and manipulate UGRID mesh topologies,
+* read, write, and manipulate HEALPix grids,
 * read, write, and create coordinates defined by geometry cells,
 * read and write netCDF4 string data-type variables,
 * read, write, and create netCDF and CDL datasets containing
diff --git a/cfdm/constructs.py b/cfdm/constructs.py
index c8fa90d14..a667533f8 100644
--- a/cfdm/constructs.py
+++ b/cfdm/constructs.py
@@ -297,7 +297,7 @@ def _del_construct(self, key, default=ValueError()):
             # --------------------------------------------------------
             # Since a cell method construct was deleted, check to see
             # if it was for climatological time, and if so reset the
-            # climatology status of approriate coordinate constructs.
+            # climatology status of appropriate coordinate constructs.
             # --------------------------------------------------------
             qualifiers = out.qualifiers()
             if "within" in qualifiers or "over" in qualifiers:
@@ -553,7 +553,7 @@ def _equals_domain_axis(
         return True
 
     def _set_climatology(self, cell_methods=None, coordinates=None):
-        """Set the climatology flag on approriate coordinate constructs.
+        """Set the climatology flag on coordinate constructs.
 
         The setting is based on the cell method constructs.
 
diff --git a/cfdm/data/data.py b/cfdm/data/data.py
index 55b855eee..0da4138a8 100644
--- a/cfdm/data/data.py
+++ b/cfdm/data/data.py
@@ -6621,6 +6621,8 @@ def rechunk(
 
             {{balance: `bool`, optional}}
 
+            {{inplace: `bool`, optional}}
+
         :Returns:
 
             `Data` or `None`
@@ -6833,8 +6835,8 @@ def reshape(self, *shape, merge_chunks=True, limit=None, inplace=False):
         """Change the shape of the data without changing its values.
 
         It assumes that the array is stored in row-major order, and
-        only allows for reshapings that collapse or merge dimensions
-        like ``(1, 2, 3, 4) -> (1, 6, 4)`` or ``(64,) -> (4, 4, 4)``.
+        only allows for reshapings that collapse or merge dimensions,
+        e.g. ``(1, 2, 3, 4) -> (1, 6, 4)`` or ``(64,) -> (4, 4, 4)``.
 
         .. versionadded:: (cfdm) 1.11.2.0
 
diff --git a/cfdm/examplefield.py b/cfdm/examplefield.py
index ffcf7f26d..3bed78d0a 100644
--- a/cfdm/examplefield.py
+++ b/cfdm/examplefield.py
@@ -1,10 +1,12 @@
+import numpy as np
+
 from .cfdmimplementation import implementation
 from .functions import CF
 
 _implementation = implementation()
 
 # The number of example fields
-_n_example_fields = 12
+_n_example_fields = 14
 
 
 def example_field(n, _implementation=_implementation):
@@ -57,6 +59,17 @@ def example_field(n, _implementation=_implementation):
 
             ``11``  Discrete sampling geometry (DSG) "trajectory"
                     features.
+
+            ``12``  A global HEALPix grid with "nested" indexing
+                    scheme at refinement level 1. The field's
+                    area-weighted global latitude-longitude means are
+                    equal to those of example field ``13``.
+
+            ``13``  A global HEALPix Multi-Order Coverage grid with
+                    "nuniq" indexing scheme representing refinement
+                    levels 1 and 2. The field's area-weighted global
+                    latitude-longitude means are equal to those of
+                    example field ``12``.
             ======  ==================================================
 
             See the examples for details.
@@ -228,6 +241,26 @@ def example_field(n, _implementation=_implementation):
                     : longitude(cf_role=trajectory_id(1), ncdim%trajectory(4)) = [[0.0, ..., 0.31]] degree_east
                     : cf_role=trajectory_id(cf_role=trajectory_id(1)) = [flight1]
 
+    >>> print(cfdm.example_field(12))
+    Field: air_temperature (ncvar%tas)
+    ----------------------------------
+    Data            : air_temperature(time(2), healpix_index(48)) K
+    Cell methods    : time(2): mean area: mean
+    Dimension coords: time(2) = [2025-06-16 00:00:00, 2025-07-16 12:00:00] proleptic_gregorian
+                    : height(1) = [1.5] m
+                    : healpix_index(healpix_index(48)) = [0, ..., 47]
+    Coord references: grid_mapping_name:healpix
+
+    >>> print(cfdm.example_field(13))
+    Field: air_temperature (ncvar%tas)
+    ----------------------------------
+    Data            : air_temperature(time(2), healpix_index(60)) K
+    Cell methods    : time(2): mean area: mean
+    Dimension coords: time(2) = [2025-06-16 00:00:00, 2025-07-16 12:00:00] proleptic_gregorian
+                    : height(1) = [1.5] m
+    Auxiliary coords: healpix_index(healpix_index(60)) = [64, ..., 63]
+    Coord references: grid_mapping_name:healpix
+
     """
     # For safety given the private second argument which we might not
     # document, otherwise a user gets an obscure error if they tried, say:
@@ -244,7 +277,9 @@ def example_field(n, _implementation=_implementation):
     CellConnectivity = _implementation.get_class("CellConnectivity")
     CellMeasure = _implementation.get_class("CellMeasure")
     CellMethod = _implementation.get_class("CellMethod")
+    CoordinateConversion = _implementation.get_class("CoordinateConversion")
     CoordinateReference = _implementation.get_class("CoordinateReference")
+    Datum = _implementation.get_class("Datum")
     DimensionCoordinate = _implementation.get_class("DimensionCoordinate")
     DomainAncillary = _implementation.get_class("DomainAncillary")
     DomainAxis = _implementation.get_class("DomainAxis")
@@ -259,6 +294,8 @@ def example_field(n, _implementation=_implementation):
 
     mesh_id = "f51e5aa5e2b0439f9fae4f04e51556f7"
 
+    field = None
+
     if n == 0:
         f = Field()
 
@@ -5290,12 +5327,544 @@ def example_field(n, _implementation=_implementation):
         #
         # field data axes
         f.set_data_axes(("domainaxis0", "domainaxis1"))
+    elif n == 12:
+        # field: air_temperature
+        field = Field()
+        field.set_properties(
+            {
+                "Conventions": "CF-1.12",
+                "standard_name": "air_temperature",
+                "units": "K",
+                "units_metadata": "temperature: on_scale",
+            }
+        )
+        field.nc_set_variable("tas")
+        data = Data(
+            [
+                [
+                    291.5,
+                    293.5,
+                    285.3,
+                    286.3,
+                    286.2,
+                    289.6,
+                    285.6,
+                    285.5,
+                    287.1,
+                    285.5,
+                    291.5,
+                    285.2,
+                    285.0,
+                    291.1,
+                    287.9,
+                    290.9,
+                    288.6,
+                    291.6,
+                    289.6,
+                    289.0,
+                    294.0,
+                    293.1,
+                    291.5,
+                    288.3,
+                    289.6,
+                    285.3,
+                    285.4,
+                    286.9,
+                    294.3,
+                    289.0,
+                    294.5,
+                    286.3,
+                    288.3,
+                    287.2,
+                    285.7,
+                    291.7,
+                    290.1,
+                    291.1,
+                    286.8,
+                    286.0,
+                    291.1,
+                    292.2,
+                    285.7,
+                    288.8,
+                    285.8,
+                    290.8,
+                    287.0,
+                    290.0,
+                ],
+                [
+                    294.2,
+                    287.7,
+                    294.6,
+                    289.5,
+                    289.2,
+                    293.0,
+                    286.8,
+                    287.8,
+                    285.2,
+                    294.0,
+                    288.1,
+                    293.5,
+                    289.6,
+                    292.5,
+                    290.0,
+                    290.5,
+                    292.9,
+                    290.7,
+                    293.6,
+                    288.3,
+                    293.5,
+                    294.0,
+                    288.7,
+                    292.0,
+                    292.9,
+                    289.5,
+                    286.8,
+                    288.3,
+                    292.6,
+                    290.3,
+                    290.8,
+                    290.4,
+                    287.7,
+                    289.9,
+                    288.4,
+                    294.7,
+                    291.4,
+                    294.7,
+                    287.6,
+                    286.5,
+                    291.4,
+                    293.0,
+                    288.8,
+                    288.8,
+                    292.3,
+                    293.7,
+                    290.1,
+                    285.9,
+                ],
+            ],
+            units="K",
+            dtype="f8",
+        )
+        field.set_data(data)
+        #
+        # domain_axis: ncdim%time
+        c = DomainAxis()
+        c.set_size(2)
+        c.nc_set_dimension("time")
+        field.set_construct(c, key="domainaxis0", copy=False)
+        #
+        # domain_axis: ncdim%cell
+        c = DomainAxis()
+        c.set_size(48)
+        c.nc_set_dimension("cell")
+        field.set_construct(c, key="domainaxis1", copy=False)
+        #
+        # domain_axis: ncdim%height
+        c = DomainAxis()
+        c.set_size(1)
+        c.nc_set_dimension("height")
+        field.set_construct(c, key="domainaxis2", copy=False)
+        #
+        # dimension_coordinate: healpix_index
+        c = DimensionCoordinate()
+        c.set_properties({"standard_name": "healpix_index"})
+        c.nc_set_variable("healpix_index")
+        data = Data(np.arange(48, dtype="int32"))
+        c.set_data(data)
+        field.set_construct(
+            c, axes=("domainaxis1",), key="dimensioncoordinate2", copy=False
+        )
+        #
+        # dimension_coordinate: time
+        c = DimensionCoordinate()
+        c.set_properties(
+            {
+                "standard_name": "time",
+                "calendar": "proleptic_gregorian",
+                "units": "days since 2025-06-01",
+            }
+        )
+        c.nc_set_variable("time")
+        data = Data(
+            [15.0, 45.5],
+            units="days since 2025-06-01",
+            calendar="proleptic_gregorian",
+            dtype="f4",
+        )
+        c.set_data(data)
+        b = Bounds()
+        b.nc_set_variable("time_bounds")
+        data = Data(
+            [[0.0, 30.0], [30.0, 61.0]],
+            units="days since 2025-06-01",
+            calendar="proleptic_gregorian",
+            dtype="f4",
+        )
+        b.set_data(data)
+        c.set_bounds(b)
+        field.set_construct(
+            c, axes=("domainaxis0",), key="dimensioncoordinate0", copy=False
+        )
+        #
+        # dimension_coordinate: height
+        c = DimensionCoordinate()
+        c.set_properties({"standard_name": "height", "units": "m"})
+        c.nc_set_variable("height")
+        data = Data([1.5], units="m", dtype="f4")
+        c.set_data(data)
+        field.set_construct(
+            c, axes=("domainaxis2",), key="dimensioncoordinate1", copy=False
+        )
+        #
+        # coordinate_reference: grid_mapping_name:healpix
+        c = CoordinateReference()
+        c.nc_set_variable("healpix")
+        c.set_coordinates({"dimensioncoordinate2"})
+        d = Datum()
+        d.set_parameters({"earth_radius": 6371000})
+        c.set_datum(d)
+        f = CoordinateConversion()
+        f.set_parameters(
+            {
+                "indexing_scheme": "nested",
+                "refinement_level": 1,
+                "grid_mapping_name": "healpix",
+            }
+        )
+        c.set_coordinate_conversion(f)
+        field.set_construct(c)
+        #
+        # cell_method: mean
+        c = CellMethod()
+        c.set_method("mean")
+        c.set_axes(("domainaxis0",))
+        field.set_construct(c)
+        #
+        # cell_method: mean
+        c = CellMethod()
+        c.set_method("mean")
+        c.set_axes(("area",))
+        field.set_construct(c)
+        #
+        # field data axes
+        field.set_data_axes(("domainaxis0", "domainaxis1"))
+    elif n == 13:
+        # field: air_temperature
+        field = Field()
+        field.set_properties(
+            {
+                "Conventions": "CF-1.12",
+                "standard_name": "air_temperature",
+                "units": "K",
+                "units_metadata": "temperature: on_scale",
+            }
+        )
+        field.nc_set_variable("tas")
+        data = Data(
+            [
+                [
+                    291.6,
+                    291.7,
+                    291.4,
+                    291.3,
+                    293.6,
+                    293.7,
+                    293.4,
+                    293.3,
+                    285.4,
+                    285.5,
+                    285.2,
+                    285.1,
+                    286.4,
+                    286.5,
+                    286.2,
+                    286.1,
+                    286.2,
+                    289.6,
+                    285.6,
+                    285.5,
+                    287.1,
+                    285.5,
+                    291.5,
+                    285.2,
+                    285.0,
+                    291.1,
+                    287.9,
+                    290.9,
+                    288.6,
+                    291.6,
+                    289.6,
+                    289.0,
+                    294.0,
+                    293.1,
+                    291.5,
+                    288.3,
+                    289.6,
+                    285.3,
+                    285.4,
+                    286.9,
+                    294.3,
+                    289.0,
+                    294.5,
+                    286.3,
+                    288.3,
+                    287.2,
+                    285.7,
+                    291.7,
+                    290.1,
+                    291.1,
+                    286.8,
+                    286.0,
+                    291.1,
+                    292.2,
+                    285.7,
+                    288.8,
+                    285.8,
+                    290.8,
+                    287.0,
+                    290.0,
+                ],
+                [
+                    294.3,
+                    294.4,
+                    294.1,
+                    294.0,
+                    287.8,
+                    287.9,
+                    287.6,
+                    287.5,
+                    294.7,
+                    294.8,
+                    294.5,
+                    294.4,
+                    289.6,
+                    289.7,
+                    289.4,
+                    289.3,
+                    289.2,
+                    293.0,
+                    286.8,
+                    287.8,
+                    285.2,
+                    294.0,
+                    288.1,
+                    293.5,
+                    289.6,
+                    292.5,
+                    290.0,
+                    290.5,
+                    292.9,
+                    290.7,
+                    293.6,
+                    288.3,
+                    293.5,
+                    294.0,
+                    288.7,
+                    292.0,
+                    292.9,
+                    289.5,
+                    286.8,
+                    288.3,
+                    292.6,
+                    290.3,
+                    290.8,
+                    290.4,
+                    287.7,
+                    289.9,
+                    288.4,
+                    294.7,
+                    291.4,
+                    294.7,
+                    287.6,
+                    286.5,
+                    291.4,
+                    293.0,
+                    288.8,
+                    288.8,
+                    292.3,
+                    293.7,
+                    290.1,
+                    285.9,
+                ],
+            ],
+            units="K",
+            dtype="f8",
+        )
+        field.set_data(data)
+        #
+        # domain_axis: ncdim%time
+        c = DomainAxis()
+        c.set_size(2)
+        c.nc_set_dimension("time")
+        field.set_construct(c, key="domainaxis0", copy=False)
+        #
+        # domain_axis: ncdim%cell
+        c = DomainAxis()
+        c.set_size(60)
+        c.nc_set_dimension("cell")
+        field.set_construct(c, key="domainaxis1", copy=False)
+        #
+        # domain_axis: ncdim%height
+        c = DomainAxis()
+        c.set_size(1)
+        c.nc_set_dimension("height")
+        field.set_construct(c, key="domainaxis2", copy=False)
+        #
+        # auxiliary_coordinate: healpix_index
+        c = AuxiliaryCoordinate()
+        c.set_properties({"standard_name": "healpix_index"})
+        c.nc_set_variable("healpix_index")
+        data = Data(
+            [
+                64,
+                65,
+                66,
+                67,
+                68,
+                69,
+                70,
+                71,
+                72,
+                73,
+                74,
+                75,
+                76,
+                77,
+                78,
+                79,
+                20,
+                21,
+                22,
+                23,
+                24,
+                25,
+                26,
+                27,
+                28,
+                29,
+                30,
+                31,
+                32,
+                33,
+                34,
+                35,
+                36,
+                37,
+                38,
+                39,
+                40,
+                41,
+                42,
+                43,
+                44,
+                45,
+                46,
+                47,
+                48,
+                49,
+                50,
+                51,
+                52,
+                53,
+                54,
+                55,
+                56,
+                57,
+                58,
+                59,
+                60,
+                61,
+                62,
+                63,
+            ],
+            dtype="i4",
+        )
+        c.set_data(data)
+        field.set_construct(
+            c, axes=("domainaxis1",), key="auxiliarycoordinate0", copy=False
+        )
+        #
+        # dimension_coordinate: time
+        c = DimensionCoordinate()
+        c.set_properties(
+            {
+                "standard_name": "time",
+                "calendar": "proleptic_gregorian",
+                "units": "days since 2025-06-01",
+            }
+        )
+        c.nc_set_variable("time")
+        data = Data(
+            [15.0, 45.5],
+            units="days since 2025-06-01",
+            calendar="proleptic_gregorian",
+            dtype="f4",
+        )
+        c.set_data(data)
+        b = Bounds()
+        b.nc_set_variable("time_bounds")
+        data = Data(
+            [[0.0, 30.0], [30.0, 61.0]],
+            units="days since 2025-06-01",
+            calendar="proleptic_gregorian",
+            dtype="f4",
+        )
+        b.set_data(data)
+        c.set_bounds(b)
+        field.set_construct(
+            c, axes=("domainaxis0",), key="dimensioncoordinate0", copy=False
+        )
+        #
+        # dimension_coordinate: height
+        c = DimensionCoordinate()
+        c.set_properties({"standard_name": "height", "units": "m"})
+        c.nc_set_variable("height")
+        data = Data([1.5], units="m", dtype="f4")
+        c.set_data(data)
+        field.set_construct(
+            c, axes=("domainaxis2",), key="dimensioncoordinate1", copy=False
+        )
+        #
+        # coordinate_reference: grid_mapping_name:healpix
+        c = CoordinateReference()
+        c.nc_set_variable("healpix")
+        c.set_coordinates({"auxiliarycoordinate0"})
+        d = Datum()
+        d.set_parameters({"earth_radius": 6371000})
+        c.set_datum(d)
+        f = CoordinateConversion()
+        f.set_parameters(
+            {
+                "indexing_scheme": "nuniq",
+                "grid_mapping_name": "healpix",
+            }
+        )
+        c.set_coordinate_conversion(f)
+        field.set_construct(c)
+        #
+        # cell_method: mean
+        c = CellMethod()
+        c.set_method("mean")
+        c.set_axes(("domainaxis0",))
+        field.set_construct(c)
+        #
+        # cell_method: mean
+        c = CellMethod()
+        c.set_method("mean")
+        c.set_axes(("area",))
+        field.set_construct(c)
+        #
+        # field data axes
+        field.set_data_axes(("domainaxis0", "domainaxis1"))
     else:
         raise ValueError(
             "Must select an example construct with an integer argument "
             f"between 0 and {_n_example_fields - 1} inclusive. Got {n!r}"
         )
 
+    if field is not None:
+        f = field
+
     return f
 
 
@@ -5317,7 +5886,6 @@ def example_fields(*n, _func=example_field):
             ======  ==================================================
             ``0``   Cell method and dimension coordinate metadata
                     constructs.
-
             ``1``   Cell method, dimension coordinate, auxiliary
                     coordinate, cell measure, coordinate reference,
                     domain ancillary and field ancillary metadata
@@ -5350,6 +5918,17 @@ def example_fields(*n, _func=example_field):
 
             ``11``  Discrete sampling geometry (DSG) "trajectory"
                     features.
+
+            ``12``  A global HEALPix grid with "nested" indices at
+                    refinement level 1. The field's area-weighted
+                    global latitude-longitude means are equal to those
+                    of example field ``13``.
+
+            ``13``  A global HEALPix Multi-Order Coverage grid with
+                    "nuniq" indices representing refinement levels 1
+                    and 2. The field's area-weighted global
+                    latitude-longitude means are equal to those of
+                    example field ``12``.
             ======  ==================================================
 
             If no individual field constructs are selected then all
@@ -5382,7 +5961,9 @@ def example_fields(*n, _func=example_field):
      <Field: air_temperature(time(2), ncdim%nMesh2_face(3)) K>,
      <Field: northward_wind(time(2), ncdim%nMesh2_edge(9)) ms-1>,
      <Field: air_pressure(time(2), ncdim%nMesh2_node(7)) hPa>,
-     <CF Field: mole_fraction_of_ozone_in_air(cf_role=trajectory_id(1), ncdim%trajectory(4)) ppb>]
+     <CF Field: mole_fraction_of_ozone_in_air(cf_role=trajectory_id(1), ncdim%trajectory(4)) ppb>
+     <Field: air_temperature(time(2), healpix_index(48)) K>,
+     <Field: air_temperature(time(2), healpix_index(60)) K>]
 
     >>> cfdm.example_fields(7, 1)
     [<Field: eastward_wind(time(3), air_pressure(1), grid_latitude(4), grid_longitude(5)) m s-1>,
@@ -5463,6 +6044,13 @@ def example_domain(n, _func=example_field):
 
             ``11``  Discrete sampling geometry (DSG) "trajectory"
                     features.
+
+            ``12``  A global HEALPix grid with "nested" indexing
+                    scheme at refinement level 1.
+
+            ``13``  A global HEALPix Multi-Order Coverage grid with
+                    "nuniq" indexing scheme representing refinement
+                    levels 1 and 2.
             ======  ==================================================
 
             See the examples for details.
@@ -5581,5 +6169,17 @@ def example_domain(n, _func=example_field):
                     : longitude(cf_role=trajectory_id(1), ncdim%trajectory(4)) = [[0.0, ..., 0.31]] degree_east
                     : cf_role=trajectory_id(cf_role=trajectory_id(1)) = [flight1]
 
+    >>> print(cfdm.example_domain(12))
+    Dimension coords: time(2) = [2025-06-16 00:00:00, 2025-07-16 12:00:00] proleptic_gregorian
+                    : height(1) = [1.5] m
+                    : healpix_index(healpix_index(48)) = [0, ..., 47]
+    Coord references: grid_mapping_name:healpix
+
+    >>> print(cfdm.example_domain(13))
+    Dimension coords: time(2) = [2025-06-16 00:00:00, 2025-07-16 12:00:00] proleptic_gregorian
+                    : height(1) = [1.5] m
+    Auxiliary coords: healpix_index(healpix_index(60)) = [64, ..., 63]
+    Coord references: grid_mapping_name:healpix
+
     """
     return _func(n).get_domain()
diff --git a/cfdm/read_write/netcdf/netcdfread.py b/cfdm/read_write/netcdf/netcdfread.py
index ed2a25710..886bbfe66 100644
--- a/cfdm/read_write/netcdf/netcdfread.py
+++ b/cfdm/read_write/netcdf/netcdfread.py
@@ -263,6 +263,7 @@ def cf_coordinate_reference_coordinates(self):
                 "latitude",
                 "longitude",
             ),
+            "healpix": ("healpix_index", "latitude", "longitude"),
             "atmosphere_ln_pressure_coordinate": (
                 "atmosphere_ln_pressure_coordinate",
             ),
diff --git a/cfdm/test/test_groups.py b/cfdm/test/test_groups.py
index 09c34d5d5..5bb7b2fb4 100644
--- a/cfdm/test/test_groups.py
+++ b/cfdm/test/test_groups.py
@@ -171,7 +171,6 @@ def test_groups(self):
         # ------------------------------------------------------------
         name = "grid_latitude"
         g.construct(name).bounds.nc_set_variable_groups(["forecast"])
-        grouped_file = "grouped_file.nc"
         cfdm.write(g, grouped_file)
 
         nc = netCDF4.Dataset(grouped_file, "r")
@@ -305,7 +304,6 @@ def test_groups_geometry(self):
         g.nc_set_component_variable("interior_ring", "interior_ring")
         g.nc_set_component_variable_groups("interior_ring", ["forecast"])
 
-        grouped_file = "grouped_file.nc"
         cfdm.write(g, grouped_file)
 
         # Check that the variable is in the right group
diff --git a/setup.py b/setup.py
index e9d5fd2be..b2d781194 100755
--- a/setup.py
+++ b/setup.py
@@ -60,6 +60,7 @@ def _get_version():
 * create new field and domain constructs in memory,
 * write and append field and domain constructs to netCDF and Zarr v3 datasets on disk,
 * read, write, and manipulate UGRID mesh topologies,
+* read, write, and manipulate HEALPix grids,
 * read, write, and create coordinates defined by geometry cells,
 * read and write netCDF4 string data-type variables,
 * read, write, and create netCDF and CDL datasets containing hierarchical groups,