diff --git a/composer.json b/composer.json
index c90e399..f6b735e 100644
--- a/composer.json
+++ b/composer.json
@@ -4,10 +4,10 @@
     "keywords":          [ ],
 
     "minimum-stability": "stable",
-    "require": {
-        "php":                  "^7.4 || ^8.0",
-        "jrosset/singleton":    "^1.0",
-        "jrosset/arrayclasses": "^1.0"
+    "require":           {
+        "php":                 "^7.4 || ^8.0",
+        "jrosset/singleton":   "^1.0",
+        "jrosset/collections": "^2.0"
     },
     "autoload":          {
         "psr-4":                 {
diff --git a/src/EnvReader/GenericConfig.php b/src/EnvReader/GenericConfig.php
index d2c7ad3..637f1ac 100644
--- a/src/EnvReader/GenericConfig.php
+++ b/src/EnvReader/GenericConfig.php
@@ -5,9 +5,9 @@ namespace jrosset\EnvReader;
 use DateTime;
 use DateTimeInterface;
 use Exception;
-use jrosset\ArrayClasses\IArrayCast;
-use jrosset\ArrayClasses\ImmutableInsensitiveCaseArrayClass;
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\IArrayCast;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
+use jrosset\Collections\InsensitiveCaseKeyImmutableCollection;
 use jrosset\Singleton\TSingleton;
 use RangeException;
 use UnexpectedValueException;
@@ -21,9 +21,9 @@ abstract class GenericConfig {
     use TSingleton;
 
     /**
-     * @var InsensitiveCaseArrayClass Current properties
+     * @var InsensitiveCaseKeyCollection Current properties
      */
-    protected InsensitiveCaseArrayClass $properties;
+    protected InsensitiveCaseKeyCollection $properties;
 
     /**
      * Initialize initial properties then read ENV file
@@ -31,7 +31,7 @@ abstract class GenericConfig {
      * @throws Exception If ENV can't be read
      */
     protected function __construct () {
-        $this->properties = new InsensitiveCaseArrayClass($this->initialProperties());
+        $this->properties = new InsensitiveCaseKeyCollection($this->initialProperties());
         $this->readConfig();
     }
 
@@ -57,10 +57,10 @@ abstract class GenericConfig {
     /**
      * Get all properties
      *
-     * @return ImmutableInsensitiveCaseArrayClass Get all properties (properties' name are in upper case)
+     * @return InsensitiveCaseKeyImmutableCollection Get all properties (properties' name are in upper case)
      */
-    public function getProperties (): ImmutableInsensitiveCaseArrayClass {
-        return $this->properties;
+    public function getProperties (): InsensitiveCaseKeyImmutableCollection {
+        return new InsensitiveCaseKeyImmutableCollection($this->properties);
     }
     /**
      * Check if a property id defined
@@ -70,7 +70,7 @@ abstract class GenericConfig {
      * @return bool Is the property defined ?
      */
     public function hasProperty (string $name): bool {
-        return $this->properties->has($name);
+        return $this->properties->exists($name);
     }
     /**
      * Get a property value
@@ -160,7 +160,7 @@ abstract class GenericConfig {
      */
     public function getPropertyAsInt (string $name, ?int $default = null): int {
         $value = $this->getProperty($name, $default === null ? null : (string)$default);
-        if (preg_match('#^\s*(?<value>[0-9]+)\s*$#', $value, $match) !== 1) {
+        if (preg_match('#^\s*(?<value>\d+)\s*$#', $value, $match) !== 1) {
             throw new RangeException('The "' . $name . '" property is not a valid integer : ' . $value);
         }
         return (int)$match['value'];
@@ -181,7 +181,7 @@ abstract class GenericConfig {
      */
     public function getPropertyAsReal (string $name, ?float $default = null): float {
         $value = $this->getProperty($name, $default === null ? null : (string)$default);
-        if (preg_match('#^\s*(?<value>[0-9]+(?:\.[0-9]+)?)\s*$#', $value, $match) !== 1) {
+        if (preg_match('#^\s*(?<value>\d+(?:\.\d+)?)\s*$#', $value, $match) !== 1) {
             throw new RangeException('The "' . $name . '" property is not a valid float value : ' . $value);
         }
         return (float)$match['value'];
@@ -228,7 +228,7 @@ abstract class GenericConfig {
             }
         }
         if ($value === false) {
-            throw new RangeException('The "' . $name . '" property is not a valid date and time : ' . $value);
+            throw new RangeException('The "' . $name . '" property is not a valid date and time');
         }
 
         return $value;
diff --git a/src/EnvReader/IniConfig.php b/src/EnvReader/IniConfig.php
index c58e54e..d3e7003 100644
--- a/src/EnvReader/IniConfig.php
+++ b/src/EnvReader/IniConfig.php
@@ -3,7 +3,7 @@
 namespace jrosset\EnvReader;
 
 use Exception;
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
 
 /**
  * A INI file configuration class
@@ -28,15 +28,15 @@ abstract class IniConfig extends GenericConfig implements IExternalConfigFile {
     /**
      * Parse an INI level to properties
      *
-     * @param array                     $iniLevelData The INI level
-     * @param InsensitiveCaseArrayClass $properties   [OUT] The out properties list
+     * @param array                        $iniLevelData The INI level
+     * @param InsensitiveCaseKeyCollection $properties   [OUT] The out properties list
      *
      * @return void
      */
-    private static function parseIniLevel (array $iniLevelData, InsensitiveCaseArrayClass $properties): void {
+    private static function parseIniLevel (array $iniLevelData, InsensitiveCaseKeyCollection $properties): void {
         foreach ($iniLevelData as $iniKey => $iniValue) {
             if (is_array($iniValue)) {
-                self::parseIniLevel($iniValue, $subProperties = new InsensitiveCaseArrayClass());
+                self::parseIniLevel($iniValue, $subProperties = new InsensitiveCaseKeyCollection());
                 $iniValue = $subProperties;
             }
 
diff --git a/src/EnvReader/TMultiLevelProperties.php b/src/EnvReader/TMultiLevelProperties.php
index 5cb1b41..e284ed1 100644
--- a/src/EnvReader/TMultiLevelProperties.php
+++ b/src/EnvReader/TMultiLevelProperties.php
@@ -2,9 +2,9 @@
 
 namespace jrosset\EnvReader;
 
-use jrosset\ArrayClasses\IArrayCast;
-use jrosset\ArrayClasses\IArrayClass;
-use jrosset\ArrayClasses\ImmutableArrayClass;
+use jrosset\Collections\IArrayCast;
+use jrosset\Collections\IImmutableCollection;
+use jrosset\Collections\InsensitiveCaseKeyImmutableCollection;
 use UnexpectedValueException;
 
 /**
@@ -23,8 +23,8 @@ trait TMultiLevelProperties {
 
         $value = $this->getProperties();
         foreach ($levels as $level) {
-            if ($value instanceof IArrayClass) {
-                if (!$value->has($level)) {
+            if ($value instanceof IImmutableCollection) {
+                if (!$value->exists($level)) {
                     return false;
                 }
                 $value = $value->get($level);
@@ -62,7 +62,7 @@ trait TMultiLevelProperties {
 
         $value = $this->getProperties();
         foreach ($levels as $level) {
-            if ($value instanceof IArrayClass) {
+            if ($value instanceof IImmutableCollection) {
                 $value = $value->get($level);
             }
             else {
@@ -88,9 +88,9 @@ trait TMultiLevelProperties {
      *
      * @param string|string[]|IArrayCast $propertyName The property name
      *
-     * @return ImmutableArrayClass The property levels
+     * @return InsensitiveCaseKeyImmutableCollection The property levels
      */
-    private function getPropertyLevels ($propertyName): ImmutableArrayClass {
+    private function getPropertyLevels ($propertyName): InsensitiveCaseKeyImmutableCollection {
         if ($propertyName instanceof IArrayCast) {
             $parts = $propertyName->toArray();
         }
@@ -100,6 +100,6 @@ trait TMultiLevelProperties {
         else {
             $parts = explode($this->getPropertySeparator(), $propertyName);
         }
-        return new ImmutableArrayClass($parts);
+        return new InsensitiveCaseKeyImmutableCollection($parts);
     }
 }
\ No newline at end of file
diff --git a/src/EnvReader/XmlStructure/AttributesXmlStructure.php b/src/EnvReader/XmlStructure/AttributesXmlStructure.php
index 20bd7cb..dc36136 100644
--- a/src/EnvReader/XmlStructure/AttributesXmlStructure.php
+++ b/src/EnvReader/XmlStructure/AttributesXmlStructure.php
@@ -2,7 +2,7 @@
 
 namespace jrosset\EnvReader\XmlStructure;
 
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
 use SimpleXMLElement;
 
 /**
@@ -14,16 +14,16 @@ class AttributesXmlStructure implements IXmlStructure {
      */
     private array $allowed;
     /**
-     * @var InsensitiveCaseArrayClass Mapping between attributes name and properties name
+     * @var InsensitiveCaseKeyCollection Mapping between attributes name and properties name
      */
-    private InsensitiveCaseArrayClass $mapping;
+    private InsensitiveCaseKeyCollection $mapping;
 
     /**
      * Initialize
      */
     public function __construct () {
         $this->allowed = [];
-        $this->mapping = new InsensitiveCaseArrayClass();
+        $this->mapping = new InsensitiveCaseKeyCollection();
     }
 
     /**
@@ -57,8 +57,8 @@ class AttributesXmlStructure implements IXmlStructure {
     /**
      * @inheritDoc
      */
-    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseArrayClass {
-        $properties = new InsensitiveCaseArrayClass();
+    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseKeyCollection {
+        $properties = new InsensitiveCaseKeyCollection();
         if (($attributes = $xmlNode->attributes()) === null) {
             return $properties;
         }
@@ -68,7 +68,7 @@ class AttributesXmlStructure implements IXmlStructure {
             if (!$allowAll && !in_array(mb_strtolower($attributeName), $this->allowed)) {
                 continue;
             }
-            $properties->set($this->mapping->get($attributeName, false) ?? $attributeName, (string)$attributeValue);
+            $properties->set($this->mapping->get($attributeName) ?? $attributeName, (string)$attributeValue);
         }
         return $properties;
     }
diff --git a/src/EnvReader/XmlStructure/ChildrenXmlStructure.php b/src/EnvReader/XmlStructure/ChildrenXmlStructure.php
index 7f8f3c9..ba75d77 100644
--- a/src/EnvReader/XmlStructure/ChildrenXmlStructure.php
+++ b/src/EnvReader/XmlStructure/ChildrenXmlStructure.php
@@ -2,8 +2,8 @@
 
 namespace jrosset\EnvReader\XmlStructure;
 
-use jrosset\ArrayClasses\ArrayClass;
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\Collection;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
 use SimpleXMLElement;
 
 /**
@@ -13,20 +13,20 @@ class ChildrenXmlStructure implements IXmlStructure {
     use TAttributeListXmlStructure;
 
     /**
-     * @var ArrayClass The children nodes
+     * @var Collection The children nodes
      */
-    private ArrayClass $childrenNodes;
+    private Collection $childrenNodes;
     /**
-     * @var InsensitiveCaseArrayClass Mapping between child node name and properties name
+     * @var Collection Mapping between child node name and properties name
      */
-    private ArrayClass $mapping;
+    private Collection $mapping;
 
     /**
      * Initialize
      */
     public function __construct () {
-        $this->childrenNodes = new ArrayClass();
-        $this->mapping = new ArrayClass();
+        $this->childrenNodes = new Collection();
+        $this->mapping = new Collection();
     }
 
     /**
@@ -49,7 +49,7 @@ class ChildrenXmlStructure implements IXmlStructure {
     /**
      * @inheritDoc
      */
-    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseArrayClass {
+    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseKeyCollection {
         $properties = $this->parseXmlAttributes($xmlNode);
 
         /** @var IXmlStructure $childNodeStructure */
@@ -58,7 +58,7 @@ class ChildrenXmlStructure implements IXmlStructure {
                 continue;
             }
             $properties->set(
-                $this->mapping->get($childNodeName, false) ?? $childNodeName,
+                $this->mapping->get($childNodeName) ?? $childNodeName,
                 $childNodeStructure->parseXml($xmlNode->$childNodeName)
             );
         }
diff --git a/src/EnvReader/XmlStructure/ListXmlStructure.php b/src/EnvReader/XmlStructure/ListXmlStructure.php
index 61d1d70..f0f6c6d 100644
--- a/src/EnvReader/XmlStructure/ListXmlStructure.php
+++ b/src/EnvReader/XmlStructure/ListXmlStructure.php
@@ -2,7 +2,7 @@
 
 namespace jrosset\EnvReader\XmlStructure;
 
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
 use SimpleXMLElement;
 
 /**
@@ -32,15 +32,15 @@ class ListXmlStructure implements IXmlStructure {
     /**
      * @inheritDoc
      */
-    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseArrayClass {
-        $properties = new InsensitiveCaseArrayClass();
+    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseKeyCollection {
+        $properties = new InsensitiveCaseKeyCollection();
         if (!isset($xmlNode->{$this->childNodeName})) {
             return $properties;
         }
 
         foreach ($xmlNode->{$this->childNodeName} as $childNode) {
             $childProperties = $this->childNodeStructure->parseXml($childNode);
-            $properties->push($childProperties);
+            $properties->add($childProperties);
         }
         return $properties;
     }
diff --git a/src/EnvReader/XmlStructure/TAttributeListXmlStructure.php b/src/EnvReader/XmlStructure/TAttributeListXmlStructure.php
index dfe3511..f4ae409 100644
--- a/src/EnvReader/XmlStructure/TAttributeListXmlStructure.php
+++ b/src/EnvReader/XmlStructure/TAttributeListXmlStructure.php
@@ -2,7 +2,7 @@
 
 namespace jrosset\EnvReader\XmlStructure;
 
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
 use SimpleXMLElement;
 
 /**
@@ -33,9 +33,9 @@ trait TAttributeListXmlStructure {
      *
      * @return mixed The extracted attributes
      */
-    protected function parseXmlAttributes (SimpleXMLElement $xmlNode): InsensitiveCaseArrayClass {
+    protected function parseXmlAttributes (SimpleXMLElement $xmlNode): InsensitiveCaseKeyCollection {
         if ($this->attributesStructure === null) {
-            return new InsensitiveCaseArrayClass();
+            return new InsensitiveCaseKeyCollection();
         }
 
         return $this->attributesStructure->parseXml($xmlNode);
diff --git a/src/EnvReader/XmlStructure/TextAndAttributesXmlStructure.php b/src/EnvReader/XmlStructure/TextAndAttributesXmlStructure.php
index 67e3797..c364288 100644
--- a/src/EnvReader/XmlStructure/TextAndAttributesXmlStructure.php
+++ b/src/EnvReader/XmlStructure/TextAndAttributesXmlStructure.php
@@ -2,7 +2,7 @@
 
 namespace jrosset\EnvReader\XmlStructure;
 
-use jrosset\ArrayClasses\InsensitiveCaseArrayClass;
+use jrosset\Collections\InsensitiveCaseKeyCollection;
 use SimpleXMLElement;
 
 /**
@@ -34,7 +34,7 @@ class TextAndAttributesXmlStructure implements IXmlStructure {
     /**
      * @inheritDoc
      */
-    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseArrayClass {
+    public function parseXml (SimpleXMLElement $xmlNode): InsensitiveCaseKeyCollection {
         $properties = $this->parseXmlAttributes($xmlNode);
         $properties->set($this->textPropertyName, $this->textXmlStructure->parseXml($xmlNode));
         return $properties;