diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f6f861400..b11b28749 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,6 +17,7 @@ jobs:
         php-version:
           - "8.0"
           - "7.4"
+          - "7.3"
 
         dependencies:
           - highest
diff --git a/composer.json b/composer.json
index 7c03375f5..b8296bbfd 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
     ],
     "license": "(MIT and proprietary)",
     "require": {
-        "php": "^7.4||^8.0",
+        "php": "^7.3||^8.0",
         "symfony/polyfill-php80": "^1.18"
     },
     "require-dev": {
diff --git a/src/CompoundPoint.php b/src/CompoundPoint.php
index f05b9c53b..1515b58a4 100644
--- a/src/CompoundPoint.php
+++ b/src/CompoundPoint.php
@@ -35,22 +35,22 @@ class CompoundPoint extends Point
      * Horizontal point.
      * @var GeographicPoint|ProjectedPoint
      */
-    protected Point $horizontalPoint;
+    protected $horizontalPoint;
 
     /**
      * Vertical point.
      */
-    protected VerticalPoint $verticalPoint;
+    protected $verticalPoint;
 
     /**
      * Coordinate reference system.
      */
-    protected Compound $crs;
+    protected $crs;
 
     /**
      * Coordinate epoch (date for which the specified coordinates represented this point).
      */
-    protected ?DateTimeImmutable $epoch;
+    protected $epoch;
 
     /**
      * Constructor.
diff --git a/src/CoordinateOperation/CRSTransformations.php b/src/CoordinateOperation/CRSTransformations.php
index 20591dbf1..6be11ea77 100644
--- a/src/CoordinateOperation/CRSTransformations.php
+++ b/src/CoordinateOperation/CRSTransformations.php
@@ -14,7 +14,7 @@
  */
 class CRSTransformations
 {
-    protected static array $sridData = [
+    protected static $sridData = [
         [
             'operation' => 'urn:ogc:def:coordinateOperation:EPSG::5166',
             'name' => 'ED50 / UTM zone 31N to ETRS89 / UTM zone 31N (1)',
diff --git a/src/CoordinateOperation/ComplexNumber.php b/src/CoordinateOperation/ComplexNumber.php
index de87fb0b8..a6ba8e45f 100644
--- a/src/CoordinateOperation/ComplexNumber.php
+++ b/src/CoordinateOperation/ComplexNumber.php
@@ -14,9 +14,9 @@
  */
 class ComplexNumber
 {
-    private float $real;
+    private $real;
 
-    private float $imaginary;
+    private $imaginary;
 
     public function __construct(float $real, float $imaginary)
     {
diff --git a/src/CoordinateOperation/CoordinateOperationParams.php b/src/CoordinateOperation/CoordinateOperationParams.php
index 7462d0239..fd397f67c 100644
--- a/src/CoordinateOperation/CoordinateOperationParams.php
+++ b/src/CoordinateOperation/CoordinateOperationParams.php
@@ -14,7 +14,7 @@
  */
 class CoordinateOperationParams
 {
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:coordinateOperation:EPSG::1024' => [
             'X-axis translation' => [
                 'value' => 601.705,
diff --git a/src/CoordinateOperation/CoordinateOperations.php b/src/CoordinateOperation/CoordinateOperations.php
index 232691131..1257b1d26 100644
--- a/src/CoordinateOperation/CoordinateOperations.php
+++ b/src/CoordinateOperation/CoordinateOperations.php
@@ -14,7 +14,7 @@
  */
 class CoordinateOperations
 {
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:coordinateOperation:EPSG::1024' => [
             'name' => 'MGI to ETRS89 (4)',
             'method' => 'urn:ogc:def:method:EPSG::9607',
diff --git a/src/CoordinateOperation/GeocentricValue.php b/src/CoordinateOperation/GeocentricValue.php
index cf2d70e9c..045568dbd 100644
--- a/src/CoordinateOperation/GeocentricValue.php
+++ b/src/CoordinateOperation/GeocentricValue.php
@@ -26,13 +26,13 @@ class GeocentricValue
 {
     protected const NEWTON_RAPHSON_CONVERGENCE = 1e-16;
 
-    private Metre$x;
+    private $x;
 
-    private Metre $y;
+    private $y;
 
-    private Metre $z;
+    private $z;
 
-    private Datum $datum;
+    private $datum;
 
     public function __construct(Length $x, Length $y, Length $z, Datum $datum)
     {
diff --git a/src/CoordinateOperation/GeographicValue.php b/src/CoordinateOperation/GeographicValue.php
index 6bdae2d7c..51f03e01b 100644
--- a/src/CoordinateOperation/GeographicValue.php
+++ b/src/CoordinateOperation/GeographicValue.php
@@ -23,13 +23,13 @@
  */
 class GeographicValue
 {
-    private Radian $latitude;
+    private $latitude;
 
-    private Radian $longitude;
+    private $longitude;
 
-    private ?Metre $height;
+    private $height;
 
-    private Datum $datum;
+    private $datum;
 
     public function __construct(Angle $latitude, Angle $longitude, ?Length $height, Datum $datum)
     {
diff --git a/src/CoordinateReferenceSystem/Compound.php b/src/CoordinateReferenceSystem/Compound.php
index a3f87f1cf..2c4e41ef1 100644
--- a/src/CoordinateReferenceSystem/Compound.php
+++ b/src/CoordinateReferenceSystem/Compound.php
@@ -2143,7 +2143,7 @@ class Compound extends CoordinateReferenceSystem
      */
     public const EPSG_WGS_84_WORLD_MERCATOR_PLUS_EGM2008_HEIGHT = 'urn:ogc:def:crs:EPSG::6893';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:crs:EPSG::3901' => [
             'name' => 'KKJ / Finland Uniform Coordinate System + N60 height',
             'horizontal_crs' => 'urn:ogc:def:crs:EPSG::2393',
@@ -3907,9 +3907,9 @@ class Compound extends CoordinateReferenceSystem
     /**
      * @var Geocentric|Geographic|Projected
      */
-    private CoordinateReferenceSystem $horizontal;
+    private $horizontal;
 
-    private Vertical $vertical;
+    private $vertical;
 
     /**
      * Compound constructor.
diff --git a/src/CoordinateReferenceSystem/CoordinateReferenceSystem.php b/src/CoordinateReferenceSystem/CoordinateReferenceSystem.php
index e7b334a8e..f116eecf6 100644
--- a/src/CoordinateReferenceSystem/CoordinateReferenceSystem.php
+++ b/src/CoordinateReferenceSystem/CoordinateReferenceSystem.php
@@ -41,11 +41,11 @@ abstract class CoordinateReferenceSystem
 
     public const CRS_SRID_PREFIX_EPSG = 'urn:ogc:def:crs:EPSG::';
 
-    protected string $srid;
+    protected $srid;
 
-    protected CoordinateSystem $coordinateSystem;
+    protected $coordinateSystem;
 
-    protected Datum $datum;
+    protected $datum;
 
     public function getSRID(): string
     {
@@ -62,7 +62,7 @@ public function getDatum(): Datum
         return $this->datum;
     }
 
-    public static function fromSRID(string $srid): self
+    public static function fromSRID(string $srid)
     {
         if (isset(Projected::getSupportedSRIDs()[$srid])) {
             return Projected::fromSRID($srid);
diff --git a/src/CoordinateReferenceSystem/Geocentric.php b/src/CoordinateReferenceSystem/Geocentric.php
index 3e5839655..891a0fe21 100644
--- a/src/CoordinateReferenceSystem/Geocentric.php
+++ b/src/CoordinateReferenceSystem/Geocentric.php
@@ -1482,7 +1482,7 @@ class Geocentric extends CoordinateReferenceSystem
      */
     public const EPSG_YEMEN_NGN96 = 'urn:ogc:def:crs:EPSG::4980';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:crs:EPSG::3822' => [
             'name' => 'TWD97',
             'coordinate_system' => 'urn:ogc:def:cs:EPSG::6500',
diff --git a/src/CoordinateReferenceSystem/Geographic.php b/src/CoordinateReferenceSystem/Geographic.php
index cdd06bfd8..17318f85d 100644
--- a/src/CoordinateReferenceSystem/Geographic.php
+++ b/src/CoordinateReferenceSystem/Geographic.php
@@ -13,7 +13,7 @@
 
 abstract class Geographic extends CoordinateReferenceSystem
 {
-    public static function fromSRID(string $srid): self
+    public static function fromSRID(string $srid)
     {
         if (isset(Geographic2D::getSupportedSRIDs()[$srid])) {
             return Geographic2D::fromSRID($srid);
diff --git a/src/CoordinateReferenceSystem/Geographic2D.php b/src/CoordinateReferenceSystem/Geographic2D.php
index b67b8a2bd..120e06ac1 100644
--- a/src/CoordinateReferenceSystem/Geographic2D.php
+++ b/src/CoordinateReferenceSystem/Geographic2D.php
@@ -3864,7 +3864,7 @@ class Geographic2D extends Geographic
      */
     public const EPSG_FK89 = 'urn:ogc:def:crs:EPSG::4753';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:crs:EPSG::3819' => [
             'name' => 'HD1909',
             'coordinate_system' => 'urn:ogc:def:cs:EPSG::6422',
diff --git a/src/CoordinateReferenceSystem/Geographic3D.php b/src/CoordinateReferenceSystem/Geographic3D.php
index da1edd62d..7cbd741ea 100644
--- a/src/CoordinateReferenceSystem/Geographic3D.php
+++ b/src/CoordinateReferenceSystem/Geographic3D.php
@@ -1535,7 +1535,7 @@ class Geographic3D extends Geographic
      */
     public const EPSG_YEMEN_NGN96 = 'urn:ogc:def:crs:EPSG::4981';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:crs:EPSG::3823' => [
             'name' => 'TWD97',
             'coordinate_system' => 'urn:ogc:def:cs:EPSG::6423',
diff --git a/src/CoordinateReferenceSystem/Projected.php b/src/CoordinateReferenceSystem/Projected.php
index 578efe561..7633df4be 100644
--- a/src/CoordinateReferenceSystem/Projected.php
+++ b/src/CoordinateReferenceSystem/Projected.php
@@ -36757,9 +36757,9 @@ class Projected extends CoordinateReferenceSystem
 
     use ProjectedSRIDData;
 
-    protected ?CoordinateReferenceSystem $baseCRS;
+    protected $baseCRS;
 
-    protected ?string $baseCRSConversionOperation;
+    protected $baseCRSConversionOperation;
 
     public function __construct(
         string $srid,
diff --git a/src/CoordinateReferenceSystem/ProjectedSRIDData.php b/src/CoordinateReferenceSystem/ProjectedSRIDData.php
index 4858b0924..9d714384c 100644
--- a/src/CoordinateReferenceSystem/ProjectedSRIDData.php
+++ b/src/CoordinateReferenceSystem/ProjectedSRIDData.php
@@ -16,7 +16,7 @@
  */
 trait ProjectedSRIDData
 {
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:crs:EPSG::2000' => [
             'name' => 'Anguilla 1957 / British West Indies Grid',
             'coordinate_system' => 'urn:ogc:def:cs:EPSG::4400',
diff --git a/src/CoordinateReferenceSystem/Vertical.php b/src/CoordinateReferenceSystem/Vertical.php
index 0ca3c0682..8a3fb1181 100644
--- a/src/CoordinateReferenceSystem/Vertical.php
+++ b/src/CoordinateReferenceSystem/Vertical.php
@@ -1734,7 +1734,7 @@ class Vertical extends CoordinateReferenceSystem
      */
     public const EPSG_YELLOW_SEA_1985_HEIGHT = 'urn:ogc:def:crs:EPSG::5737';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:crs:EPSG::3855' => [
             'name' => 'EGM2008 height',
             'coordinate_system' => 'urn:ogc:def:cs:EPSG::6499',
diff --git a/src/CoordinateSystem/Axis.php b/src/CoordinateSystem/Axis.php
index d28c1f638..6b63b28da 100644
--- a/src/CoordinateSystem/Axis.php
+++ b/src/CoordinateSystem/Axis.php
@@ -36,13 +36,13 @@ class Axis
 
     public const WESTING = 'Westing';
 
-    private string $orientation;
+    private $orientation;
 
-    private string $abbreviation;
+    private $abbreviation;
 
-    private string $name;
+    private $name;
 
-    private string $unitOfMeasureId;
+    private $unitOfMeasureId;
 
     public function __construct(
         string $orientation,
diff --git a/src/CoordinateSystem/Cartesian.php b/src/CoordinateSystem/Cartesian.php
index b66248f1b..579b9af04 100644
--- a/src/CoordinateSystem/Cartesian.php
+++ b/src/CoordinateSystem/Cartesian.php
@@ -561,7 +561,7 @@ class Cartesian extends CoordinateSystem
      */
     public const EPSG_AXES_WESTING_SOUTHING_Y_X_ORIENTATIONS_WEST_SOUTH_UOM_M = 'urn:ogc:def:cs:EPSG::6503';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:cs:EPSG::1024' => [
             'name' => '. Axes: easting, northing (M,P). Orientations east, north. UoM m.',
             'axes' => [
diff --git a/src/CoordinateSystem/CoordinateSystem.php b/src/CoordinateSystem/CoordinateSystem.php
index b532a65b0..c24682899 100644
--- a/src/CoordinateSystem/CoordinateSystem.php
+++ b/src/CoordinateSystem/CoordinateSystem.php
@@ -20,12 +20,12 @@ abstract class CoordinateSystem
 
     public const CS_TYPE_VERTICAL = 'vertical';
 
-    protected string $srid;
+    protected $srid;
 
     /**
      * @var Axis[]
      */
-    protected array $axes;
+    protected $axes;
 
     public function __construct(
         string $srid,
diff --git a/src/CoordinateSystem/Ellipsoidal.php b/src/CoordinateSystem/Ellipsoidal.php
index 42b555ab6..31575243a 100644
--- a/src/CoordinateSystem/Ellipsoidal.php
+++ b/src/CoordinateSystem/Ellipsoidal.php
@@ -58,7 +58,7 @@ class Ellipsoidal extends CoordinateSystem
      */
     public const EPSG_AXES_LONGITUDE_LATITUDE_ORIENTATIONS_EAST_NORTH_UOM_DEGREE = 'urn:ogc:def:cs:EPSG::6424';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:cs:EPSG::6403' => [
             'name' => '. Axes: latitude, longitude. Orientations: north, east. UoM: grads.',
             'axes' => [
diff --git a/src/CoordinateSystem/Vertical.php b/src/CoordinateSystem/Vertical.php
index a97fc48a6..779b5f9cb 100644
--- a/src/CoordinateSystem/Vertical.php
+++ b/src/CoordinateSystem/Vertical.php
@@ -62,7 +62,7 @@ class Vertical extends CoordinateSystem
      */
     public const EPSG_AXIS_HEIGHT_H_ORIENTATION_UP_UOM_M = 'urn:ogc:def:cs:EPSG::6499';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:cs:EPSG::1030' => [
             'name' => '. Axis: height (H). Orientation: up. UoM: ft.',
             'axes' => [
diff --git a/src/Datum/Datum.php b/src/Datum/Datum.php
index 3ba529837..d31b35edf 100644
--- a/src/Datum/Datum.php
+++ b/src/Datum/Datum.php
@@ -7466,7 +7466,7 @@ class Datum
      */
     public const EPSG_FK89 = 'urn:ogc:def:datum:EPSG::6753';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:datum:EPSG::1024' => [
             'name' => 'Hungarian Datum 1909',
             'type' => 'geodetic',
@@ -13729,13 +13729,13 @@ class Datum
 
     public const DATUM_TYPE_ENSEMBLE = 'ensemble';
 
-    protected string $datumType;
+    protected $datumType;
 
-    protected ?Ellipsoid $ellipsoid;
+    protected $ellipsoid;
 
-    protected ?PrimeMeridian $primeMeridian;
+    protected $primeMeridian;
 
-    protected ?float $frameReferenceEpoch;
+    protected $frameReferenceEpoch;
 
     public function __construct(
         string $datumType,
diff --git a/src/Datum/Ellipsoid.php b/src/Datum/Ellipsoid.php
index 113ad277f..f6bcc07d8 100644
--- a/src/Datum/Ellipsoid.php
+++ b/src/Datum/Ellipsoid.php
@@ -353,7 +353,7 @@ class Ellipsoid
      */
     public const EPSG_ZACH_1812 = 'urn:ogc:def:ellipsoid:EPSG::1026';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:ellipsoid:EPSG::1024' => [
             'name' => 'CGCS2000',
             'semi_major_axis' => 6378137.0,
@@ -656,9 +656,9 @@ class Ellipsoid
         ],
     ];
 
-    protected Length $semiMajorAxis;
+    protected $semiMajorAxis;
 
-    protected Length $semiMinorAxis;
+    protected $semiMinorAxis;
 
     public function __construct(Length $semiMajorAxis, Length $semiMinorAxis)
     {
diff --git a/src/Datum/PrimeMeridian.php b/src/Datum/PrimeMeridian.php
index 8e253fa58..db6ca6872 100644
--- a/src/Datum/PrimeMeridian.php
+++ b/src/Datum/PrimeMeridian.php
@@ -97,7 +97,7 @@ class PrimeMeridian
      */
     public const EPSG_STOCKHOLM = 'urn:ogc:def:meridian:EPSG::8911';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:meridian:EPSG::8901' => [
             'name' => 'Greenwich',
             'greenwich_longitude' => 0.0,
@@ -170,9 +170,9 @@ class PrimeMeridian
         ],
     ];
 
-    private string $name;
+    private $name;
 
-    private Angle $greenwichLongitude;
+    private $greenwichLongitude;
 
     public function __construct(string $name, Angle $greenwichLongitude)
     {
diff --git a/src/EPSG/Import/AddNewConstantsVisitor.php b/src/EPSG/Import/AddNewConstantsVisitor.php
index c455b742c..c92f4ff1c 100644
--- a/src/EPSG/Import/AddNewConstantsVisitor.php
+++ b/src/EPSG/Import/AddNewConstantsVisitor.php
@@ -25,9 +25,9 @@
 
 class AddNewConstantsVisitor extends NodeVisitorAbstract
 {
-    private array $constants;
+    private $constants;
 
-    private string $visibility;
+    private $visibility;
 
     public function __construct(array $constants, string $visibility)
     {
diff --git a/src/EPSG/Import/AddNewDataVisitor.php b/src/EPSG/Import/AddNewDataVisitor.php
index 0cf71c286..b2644ff8f 100644
--- a/src/EPSG/Import/AddNewDataVisitor.php
+++ b/src/EPSG/Import/AddNewDataVisitor.php
@@ -18,7 +18,7 @@
 
 class AddNewDataVisitor extends NodeVisitorAbstract
 {
-    private array $data;
+    private $data;
 
     public function __construct(array $data)
     {
diff --git a/src/EPSG/Import/EPSGImporter.php b/src/EPSG/Import/EPSGImporter.php
index e2ef07171..cedd87cf2 100644
--- a/src/EPSG/Import/EPSGImporter.php
+++ b/src/EPSG/Import/EPSGImporter.php
@@ -30,9 +30,9 @@
 
 class EPSGImporter
 {
-    private string $resourceDir;
+    private $resourceDir;
 
-    private string $sourceDir;
+    private $sourceDir;
 
     private const BOM = "\xEF\xBB\xBF";
 
diff --git a/src/GeocentricPoint.php b/src/GeocentricPoint.php
index 4b632d565..023eac02d 100644
--- a/src/GeocentricPoint.php
+++ b/src/GeocentricPoint.php
@@ -43,27 +43,27 @@ class GeocentricPoint extends Point
     /**
      * X co-ordinate.
      */
-    protected Length $x;
+    protected $x;
 
     /**
      * Y co-ordinate.
      */
-    protected Length $y;
+    protected $y;
 
     /**
      * Z co-ordinate.
      */
-    protected Length $z;
+    protected $z;
 
     /**
      * Coordinate reference system.
      */
-    protected Geocentric $crs;
+    protected $crs;
 
     /**
      * Coordinate epoch (date for which the specified coordinates represented this point).
      */
-    protected ?DateTimeImmutable $epoch;
+    protected $epoch;
 
     protected function __construct(Length $x, Length $y, Length $z, Geocentric $crs, ?DateTimeInterface $epoch = null)
     {
diff --git a/src/GeographicPoint.php b/src/GeographicPoint.php
index 7f45aea93..1fc39f909 100644
--- a/src/GeographicPoint.php
+++ b/src/GeographicPoint.php
@@ -64,27 +64,27 @@ class GeographicPoint extends Point
     /**
      * Latitude.
      */
-    protected Angle $latitude;
+    protected $latitude;
 
     /**
      * Longitude.
      */
-    protected Angle $longitude;
+    protected $longitude;
 
     /**
      * Height above ellipsoid (N.B. *not* height above ground, sea-level or anything else tangible).
      */
-    protected ?Length $height;
+    protected $height;
 
     /**
      * Coordinate reference system.
      */
-    protected Geographic $crs;
+    protected $crs;
 
     /**
      * Coordinate epoch (date for which the specified coordinates represented this point).
      */
-    protected ?DateTimeImmutable $epoch;
+    protected $epoch;
 
     protected function __construct(Angle $latitude, Angle $longitude, ?Length $height, Geographic $crs, ?DateTimeInterface $epoch = null)
     {
diff --git a/src/Point.php b/src/Point.php
index 689290c49..58988635e 100644
--- a/src/Point.php
+++ b/src/Point.php
@@ -270,7 +270,7 @@ protected static function asin(float $num): float
         return asin($num);
     }
 
-    abstract public function getCRS(): CoordinateReferenceSystem;
+    abstract public function getCRS();
 
     abstract public function getCoordinateEpoch(): ?DateTimeImmutable;
 
diff --git a/src/ProjectedPoint.php b/src/ProjectedPoint.php
index f3c7d4a3d..5ff556231 100644
--- a/src/ProjectedPoint.php
+++ b/src/ProjectedPoint.php
@@ -56,32 +56,32 @@ class ProjectedPoint extends Point
     /**
      * Easting.
      */
-    protected Length $easting;
+    protected $easting;
 
     /**
      * Northing.
      */
-    protected Length $northing;
+    protected $northing;
 
     /**
      * Westing.
      */
-    protected Length $westing;
+    protected $westing;
 
     /**
      * Southing.
      */
-    protected Length $southing;
+    protected $southing;
 
     /**
      * Coordinate reference system.
      */
-    protected Projected $crs;
+    protected $crs;
 
     /**
      * Coordinate epoch (date for which the specified coordinates represented this point).
      */
-    protected ?DateTimeImmutable $epoch;
+    protected $epoch;
 
     protected function __construct(?Length $easting, ?Length $northing, ?Length $westing, ?Length $southing, Projected $crs, ?DateTimeInterface $epoch = null)
     {
diff --git a/src/UnitOfMeasure/Angle/Angle.php b/src/UnitOfMeasure/Angle/Angle.php
index 786a598fa..5ec666732 100644
--- a/src/UnitOfMeasure/Angle/Angle.php
+++ b/src/UnitOfMeasure/Angle/Angle.php
@@ -133,7 +133,7 @@ abstract class Angle implements UnitOfMeasure
      */
     public const EPSG_SEXAGESIMAL_DMS = 'urn:ogc:def:uom:EPSG::9110';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:uom:EPSG::1031' => [
             'name' => 'milliarc-second',
         ],
diff --git a/src/UnitOfMeasure/Angle/ArcSecond.php b/src/UnitOfMeasure/Angle/ArcSecond.php
index 944b047e7..e989cf33c 100644
--- a/src/UnitOfMeasure/Angle/ArcSecond.php
+++ b/src/UnitOfMeasure/Angle/ArcSecond.php
@@ -10,7 +10,7 @@
 
 class ArcSecond extends Angle
 {
-    private float $angle;
+    private $angle;
 
     public function __construct(float $angle)
     {
diff --git a/src/UnitOfMeasure/Angle/Degree.php b/src/UnitOfMeasure/Angle/Degree.php
index 0a78cc8ca..bfe93731e 100644
--- a/src/UnitOfMeasure/Angle/Degree.php
+++ b/src/UnitOfMeasure/Angle/Degree.php
@@ -17,7 +17,7 @@
 
 class Degree extends Angle
 {
-    private float $angle;
+    private $angle;
 
     public function __construct(float $angle)
     {
diff --git a/src/UnitOfMeasure/Angle/Grad.php b/src/UnitOfMeasure/Angle/Grad.php
index dc08c4808..5d6bdb628 100644
--- a/src/UnitOfMeasure/Angle/Grad.php
+++ b/src/UnitOfMeasure/Angle/Grad.php
@@ -10,7 +10,7 @@
 
 class Grad extends Angle
 {
-    private float $angle;
+    private $angle;
 
     public function __construct(float $angle)
     {
diff --git a/src/UnitOfMeasure/Angle/Radian.php b/src/UnitOfMeasure/Angle/Radian.php
index 47549d2bd..70bb21b19 100644
--- a/src/UnitOfMeasure/Angle/Radian.php
+++ b/src/UnitOfMeasure/Angle/Radian.php
@@ -10,7 +10,7 @@
 
 class Radian extends Angle
 {
-    private float $angle;
+    private $angle;
 
     public function __construct(float $angle)
     {
diff --git a/src/UnitOfMeasure/Length/BritishChain1895BenoitB.php b/src/UnitOfMeasure/Length/BritishChain1895BenoitB.php
index 02d316da5..43068deec 100644
--- a/src/UnitOfMeasure/Length/BritishChain1895BenoitB.php
+++ b/src/UnitOfMeasure/Length/BritishChain1895BenoitB.php
@@ -10,7 +10,7 @@
 
 class BritishChain1895BenoitB extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/BritishChain1922Sears.php b/src/UnitOfMeasure/Length/BritishChain1922Sears.php
index 5be502129..2e7ccf1d4 100644
--- a/src/UnitOfMeasure/Length/BritishChain1922Sears.php
+++ b/src/UnitOfMeasure/Length/BritishChain1922Sears.php
@@ -10,7 +10,7 @@
 
 class BritishChain1922Sears extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/BritishChain1922SearsTruncated.php b/src/UnitOfMeasure/Length/BritishChain1922SearsTruncated.php
index 79d629b0b..aa6f77d12 100644
--- a/src/UnitOfMeasure/Length/BritishChain1922SearsTruncated.php
+++ b/src/UnitOfMeasure/Length/BritishChain1922SearsTruncated.php
@@ -10,7 +10,7 @@
 
 class BritishChain1922SearsTruncated extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/BritishFoot1922Sears.php b/src/UnitOfMeasure/Length/BritishFoot1922Sears.php
index ef683a02c..14fd792f5 100644
--- a/src/UnitOfMeasure/Length/BritishFoot1922Sears.php
+++ b/src/UnitOfMeasure/Length/BritishFoot1922Sears.php
@@ -10,7 +10,7 @@
 
 class BritishFoot1922Sears extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/BritishFoot1936.php b/src/UnitOfMeasure/Length/BritishFoot1936.php
index 27be180a1..32f1e616e 100644
--- a/src/UnitOfMeasure/Length/BritishFoot1936.php
+++ b/src/UnitOfMeasure/Length/BritishFoot1936.php
@@ -10,7 +10,7 @@
 
 class BritishFoot1936 extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/BritishYard1922Sears.php b/src/UnitOfMeasure/Length/BritishYard1922Sears.php
index 422acd0cb..ce314bc0f 100644
--- a/src/UnitOfMeasure/Length/BritishYard1922Sears.php
+++ b/src/UnitOfMeasure/Length/BritishYard1922Sears.php
@@ -10,7 +10,7 @@
 
 class BritishYard1922Sears extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/Centimetre.php b/src/UnitOfMeasure/Length/Centimetre.php
index be798d70d..3d159ac82 100644
--- a/src/UnitOfMeasure/Length/Centimetre.php
+++ b/src/UnitOfMeasure/Length/Centimetre.php
@@ -10,7 +10,7 @@
 
 class Centimetre extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/ClarkeFoot.php b/src/UnitOfMeasure/Length/ClarkeFoot.php
index f5bbc45f8..b2c1704d6 100644
--- a/src/UnitOfMeasure/Length/ClarkeFoot.php
+++ b/src/UnitOfMeasure/Length/ClarkeFoot.php
@@ -10,7 +10,7 @@
 
 class ClarkeFoot extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/ClarkeLink.php b/src/UnitOfMeasure/Length/ClarkeLink.php
index 77e0e4d70..2efe334be 100644
--- a/src/UnitOfMeasure/Length/ClarkeLink.php
+++ b/src/UnitOfMeasure/Length/ClarkeLink.php
@@ -10,7 +10,7 @@
 
 class ClarkeLink extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/ClarkeYard.php b/src/UnitOfMeasure/Length/ClarkeYard.php
index ff8f47c28..62b20d9c4 100644
--- a/src/UnitOfMeasure/Length/ClarkeYard.php
+++ b/src/UnitOfMeasure/Length/ClarkeYard.php
@@ -10,7 +10,7 @@
 
 class ClarkeYard extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/Foot.php b/src/UnitOfMeasure/Length/Foot.php
index ced2133f7..8108813c7 100644
--- a/src/UnitOfMeasure/Length/Foot.php
+++ b/src/UnitOfMeasure/Length/Foot.php
@@ -15,7 +15,7 @@
  */
 class Foot extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/GermanLegalMetre.php b/src/UnitOfMeasure/Length/GermanLegalMetre.php
index 4c9d34f83..d684a294d 100644
--- a/src/UnitOfMeasure/Length/GermanLegalMetre.php
+++ b/src/UnitOfMeasure/Length/GermanLegalMetre.php
@@ -14,7 +14,7 @@
  */
 class GermanLegalMetre extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/GoldCoastFoot.php b/src/UnitOfMeasure/Length/GoldCoastFoot.php
index a7b8f4536..0f1a4f6a5 100644
--- a/src/UnitOfMeasure/Length/GoldCoastFoot.php
+++ b/src/UnitOfMeasure/Length/GoldCoastFoot.php
@@ -13,7 +13,7 @@
  */
 class GoldCoastFoot extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/IndianFoot.php b/src/UnitOfMeasure/Length/IndianFoot.php
index 2987cfaab..5c1ee0e28 100644
--- a/src/UnitOfMeasure/Length/IndianFoot.php
+++ b/src/UnitOfMeasure/Length/IndianFoot.php
@@ -10,7 +10,7 @@
 
 class IndianFoot extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/IndianYard.php b/src/UnitOfMeasure/Length/IndianYard.php
index 4792060f1..d0f5e3ba1 100644
--- a/src/UnitOfMeasure/Length/IndianYard.php
+++ b/src/UnitOfMeasure/Length/IndianYard.php
@@ -10,7 +10,7 @@
 
 class IndianYard extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/Kilometre.php b/src/UnitOfMeasure/Length/Kilometre.php
index 657a9767b..77e890d61 100644
--- a/src/UnitOfMeasure/Length/Kilometre.php
+++ b/src/UnitOfMeasure/Length/Kilometre.php
@@ -10,7 +10,7 @@
 
 class Kilometre extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/Length.php b/src/UnitOfMeasure/Length/Length.php
index 5c714fad2..795ae1169 100644
--- a/src/UnitOfMeasure/Length/Length.php
+++ b/src/UnitOfMeasure/Length/Length.php
@@ -144,7 +144,7 @@ abstract class Length implements UnitOfMeasure
      */
     public const EPSG_MILLIMETRE = 'urn:ogc:def:uom:EPSG::1025';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:uom:EPSG::1025' => [
             'name' => 'millimetre',
         ],
diff --git a/src/UnitOfMeasure/Length/Link.php b/src/UnitOfMeasure/Length/Link.php
index 5d449985f..b2266d22a 100644
--- a/src/UnitOfMeasure/Length/Link.php
+++ b/src/UnitOfMeasure/Length/Link.php
@@ -10,7 +10,7 @@
 
 class Link extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/Metre.php b/src/UnitOfMeasure/Length/Metre.php
index 901f72230..fd4031f56 100644
--- a/src/UnitOfMeasure/Length/Metre.php
+++ b/src/UnitOfMeasure/Length/Metre.php
@@ -10,7 +10,7 @@
 
 class Metre extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/Millimetre.php b/src/UnitOfMeasure/Length/Millimetre.php
index cef4e589e..1df9e5f81 100644
--- a/src/UnitOfMeasure/Length/Millimetre.php
+++ b/src/UnitOfMeasure/Length/Millimetre.php
@@ -10,7 +10,7 @@
 
 class Millimetre extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Length/USSurveyFoot.php b/src/UnitOfMeasure/Length/USSurveyFoot.php
index a53a6ecd6..1c933cde4 100644
--- a/src/UnitOfMeasure/Length/USSurveyFoot.php
+++ b/src/UnitOfMeasure/Length/USSurveyFoot.php
@@ -15,7 +15,7 @@
  */
 class USSurveyFoot extends Length
 {
-    private float $length;
+    private $length;
 
     public function __construct(float $length)
     {
diff --git a/src/UnitOfMeasure/Rate.php b/src/UnitOfMeasure/Rate.php
index f85734000..cf173b74d 100644
--- a/src/UnitOfMeasure/Rate.php
+++ b/src/UnitOfMeasure/Rate.php
@@ -67,7 +67,7 @@ class Rate implements UnitOfMeasure
      */
     public const EPSG_PARTS_PER_MILLION_PER_YEAR = 'urn:ogc:def:uom:EPSG::1041';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:uom:EPSG::1027' => [
             'name' => 'millimetres per year',
         ],
@@ -91,9 +91,9 @@ class Rate implements UnitOfMeasure
         ],
     ];
 
-    private UnitOfMeasure $change;
+    private $change;
 
-    private Time $time;
+    private $time;
 
     public function __construct(UnitOfMeasure $change, Time $time)
     {
diff --git a/src/UnitOfMeasure/Scale/Coefficient.php b/src/UnitOfMeasure/Scale/Coefficient.php
index cad1727a7..882952830 100644
--- a/src/UnitOfMeasure/Scale/Coefficient.php
+++ b/src/UnitOfMeasure/Scale/Coefficient.php
@@ -10,7 +10,7 @@
 
 class Coefficient extends Scale
 {
-    private float $scale;
+    private $scale;
 
     public function __construct(float $scale)
     {
diff --git a/src/UnitOfMeasure/Scale/PartsPerBillion.php b/src/UnitOfMeasure/Scale/PartsPerBillion.php
index eb0bdbfa5..743949859 100644
--- a/src/UnitOfMeasure/Scale/PartsPerBillion.php
+++ b/src/UnitOfMeasure/Scale/PartsPerBillion.php
@@ -10,7 +10,7 @@
 
 class PartsPerBillion extends Scale
 {
-    private float $scale;
+    private $scale;
 
     public function __construct(float $scale)
     {
diff --git a/src/UnitOfMeasure/Scale/PartsPerMillion.php b/src/UnitOfMeasure/Scale/PartsPerMillion.php
index 377e69f02..27e76fada 100644
--- a/src/UnitOfMeasure/Scale/PartsPerMillion.php
+++ b/src/UnitOfMeasure/Scale/PartsPerMillion.php
@@ -10,7 +10,7 @@
 
 class PartsPerMillion extends Scale
 {
-    private float $scale;
+    private $scale;
 
     public function __construct(float $scale)
     {
diff --git a/src/UnitOfMeasure/Scale/Scale.php b/src/UnitOfMeasure/Scale/Scale.php
index ecf4c4baa..66836d490 100644
--- a/src/UnitOfMeasure/Scale/Scale.php
+++ b/src/UnitOfMeasure/Scale/Scale.php
@@ -40,7 +40,7 @@ abstract class Scale implements UnitOfMeasure
      */
     public const EPSG_UNITY = 'urn:ogc:def:uom:EPSG::9201';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:uom:EPSG::1028' => [
             'name' => 'parts per billion',
         ],
diff --git a/src/UnitOfMeasure/Scale/Unity.php b/src/UnitOfMeasure/Scale/Unity.php
index a41dea894..b96f29d07 100644
--- a/src/UnitOfMeasure/Scale/Unity.php
+++ b/src/UnitOfMeasure/Scale/Unity.php
@@ -10,7 +10,7 @@
 
 class Unity extends Scale
 {
-    private float $scale;
+    private $scale;
 
     public function __construct(float $scale)
     {
diff --git a/src/UnitOfMeasure/Time/Time.php b/src/UnitOfMeasure/Time/Time.php
index 8b6c56feb..ee0d336c2 100644
--- a/src/UnitOfMeasure/Time/Time.php
+++ b/src/UnitOfMeasure/Time/Time.php
@@ -19,7 +19,7 @@ abstract class Time implements UnitOfMeasure
      */
     public const EPSG_YEAR = 'urn:ogc:def:uom:EPSG::1029';
 
-    protected static array $sridData = [
+    protected static $sridData = [
         'urn:ogc:def:uom:EPSG::1029' => [
             'name' => 'year',
         ],
diff --git a/src/UnitOfMeasure/Time/Year.php b/src/UnitOfMeasure/Time/Year.php
index 157c32c48..8dcc390b4 100644
--- a/src/UnitOfMeasure/Time/Year.php
+++ b/src/UnitOfMeasure/Time/Year.php
@@ -14,7 +14,7 @@
 
 class Year extends Time
 {
-    private float $time;
+    private $time;
 
     public function __construct(float $time)
     {
diff --git a/src/VerticalPoint.php b/src/VerticalPoint.php
index ba8802c40..d6411cca2 100644
--- a/src/VerticalPoint.php
+++ b/src/VerticalPoint.php
@@ -25,17 +25,17 @@ class VerticalPoint extends Point
     /**
      * Height.
      */
-    protected Length $height;
+    protected $height;
 
     /**
      * Coordinate reference system.
      */
-    protected Vertical $crs;
+    protected $crs;
 
     /**
      * Coordinate epoch (date for which the specified coordinates represented this point).
      */
-    protected ?DateTimeImmutable $epoch;
+    protected $epoch;
 
     /**
      * Constructor.