diff --git a/src/ArrayClasses/IArrayClass.php b/src/ArrayClasses/IArrayClass.php
index 4971443..2e698e6 100644
--- a/src/ArrayClasses/IArrayClass.php
+++ b/src/ArrayClasses/IArrayClass.php
@@ -2,6 +2,11 @@
 
 namespace jrosset\ArrayClasses;
 
+/**
+ * Interface for array classes
+ *
+ * @see IImmutableArrayClass Immutable version
+ */
 interface IArrayClass extends IImmutableArrayClass {
     /**
      * Create or replace a cell
@@ -15,11 +20,12 @@ interface IArrayClass extends IImmutableArrayClass {
     /**
      * Remove a cell
      *
-     * @param mixed $cellName The cell name/offset
+     * @param mixed $cellName                    The cell name/offset
+     * @param bool  $throwsForNonExistentElement Throws an exception for nonexistent elements ?
      *
      * @return $this
      */
-    public function del ($cellName): self;
+    public function del ($cellName, ?bool $throwsForNonExistentElement = null): self;
 
     /**
      * Create an immutable copy
diff --git a/src/ArrayClasses/IImmutableArrayClass.php b/src/ArrayClasses/IImmutableArrayClass.php
index 3c7fb1e..9908cef 100644
--- a/src/ArrayClasses/IImmutableArrayClass.php
+++ b/src/ArrayClasses/IImmutableArrayClass.php
@@ -8,6 +8,11 @@ use IteratorAggregate;
 use JsonSerializable;
 use Serializable;
 
+/**
+ * Interface for immutable array classes
+ *
+ * @see IArrayClass Mutable version
+ */
 interface IImmutableArrayClass extends IteratorAggregate, JsonSerializable, Serializable, Countable, ArrayAccess, IArrayCast {
     /**
      * Check if a cell exists
@@ -20,11 +25,12 @@ interface IImmutableArrayClass extends IteratorAggregate, JsonSerializable, Seri
     /**
      * Get the value of a cell
      *
-     * @param mixed $cellName The cell name/offset
+     * @param mixed $cellName                    The cell name/offset
+     * @param bool  $throwsForNonExistentElement Throws an exception for nonexistent elements ?
      *
      * @return mixed The cell value
      */
-    public function get ($cellName);
+    public function get ($cellName, ?bool $throwsForNonExistentElement = null);
 
     /**
      * Create a mutable copy
diff --git a/src/ArrayClasses/ImmutableInsensitiveCaseArrayClass.php b/src/ArrayClasses/ImmutableInsensitiveCaseArrayClass.php
new file mode 100644
index 0000000..bf523d4
--- /dev/null
+++ b/src/ArrayClasses/ImmutableInsensitiveCaseArrayClass.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace jrosset\ArrayClasses;
+
+/**
+ * An immutable array with insensitive case cell name
+ */
+class ImmutableInsensitiveCaseArrayClass implements IImmutableArrayClass {
+    use TImmutableInternalArray {
+        has as private has__TImmutableInternalArray;
+        get as private get__TImmutableInternalArray;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function has ($cellName): bool {
+        return $this->has__TImmutableInternalArray(mb_strtolower($cellName));
+    }
+    /**
+     * @inheritDoc
+     */
+    public function get ($cellName, ?bool $throwsForNonExistentElement = null) {
+        return $this->get__TImmutableInternalArray(mb_strtolower($cellName), $throwsForNonExistentElement);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function toMutable (): IArrayClass {
+        return new InsensitiveCaseArrayClass($this->array, $this->throwsForNonExistentElement());
+    }
+}
\ No newline at end of file
diff --git a/src/ArrayClasses/InsensitiveCaseArrayClass.php b/src/ArrayClasses/InsensitiveCaseArrayClass.php
new file mode 100644
index 0000000..2978ad5
--- /dev/null
+++ b/src/ArrayClasses/InsensitiveCaseArrayClass.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace jrosset\ArrayClasses;
+
+/**
+ * An array with insensitive case cell name
+ */
+class InsensitiveCaseArrayClass extends ImmutableInsensitiveCaseArrayClass implements IArrayClass {
+    use TInternalArray {
+        set as private set__TInternalArray;
+        del as private del__TInternalArray;
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function set ($cellName, $cellValue): self {
+        return $this->set__TInternalArray(mb_strtolower($cellName), $cellValue);
+    }
+    /**
+     * @inheritDoc
+     */
+    public function del ($cellName, ?bool $throwsForNonExistentElement = null): self {
+        return $this->del__TInternalArray(mb_strtolower($cellName), $throwsForNonExistentElement);
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function toImmutable (): IImmutableArrayClass {
+        return new ImmutableInsensitiveCaseArrayClass($this->array, $this->throwsForNonExistentElement());
+    }
+}
\ No newline at end of file
diff --git a/src/ArrayClasses/TImmutableInternalArray.php b/src/ArrayClasses/TImmutableInternalArray.php
index 0ec0e8d..d8fbce8 100644
--- a/src/ArrayClasses/TImmutableInternalArray.php
+++ b/src/ArrayClasses/TImmutableInternalArray.php
@@ -53,26 +53,17 @@ trait TImmutableInternalArray {
     }
 
     /**
-     * Check if a cell offset exists
-     *
-     * @param mixed $offset The cell offset
-     *
-     * @return bool True if the cell offset exists
+     * @inheritDoc
      */
-    public function has ($offset): bool {
-        return array_key_exists($offset, $this->array);
+    public function has ($cellName): bool {
+        return array_key_exists($cellName, $this->array);
     }
     /**
-     * Get the value of a cell
-     *
-     * @param mixed     $offset                      The cell offset
-     * @param bool|null $throwsForNonExistentElement If set, temporarily override {@see ImmutableArrayClass::$throwsForNonExistentElement}
-     *
-     * @return mixed|null The cell value
+     * @inheritDoc
      */
-    public function get ($offset, ?bool $throwsForNonExistentElement = null) {
-        if ($this->has($offset)) {
-            return $this->array[$offset];
+    public function get ($cellName, ?bool $throwsForNonExistentElement = null) {
+        if ($this->has($cellName)) {
+            return $this->array[$cellName];
         }
         if ($throwsForNonExistentElement ?? $this->throwsForNonExistentElement()) {
             throw new OutOfRangeException();
diff --git a/src/ArrayClasses/TInternalArray.php b/src/ArrayClasses/TInternalArray.php
index e9ba1d0..a3a4036 100644
--- a/src/ArrayClasses/TInternalArray.php
+++ b/src/ArrayClasses/TInternalArray.php
@@ -6,30 +6,30 @@ use OutOfRangeException;
 
 trait TInternalArray {
     /**
-     * Set or replace a cell value
+     * Create or replace a cell value
      *
-     * @param mixed $offset The cell offset
-     * @param mixed $value  The cell new value
+     * @param mixed $cellName  The cell name/offset
+     * @param mixed $cellValue The cell new value
      *
      * @return $this
      */
-    public function set ($offset, $value): self {
-        $this->array[$offset] = $value;
+    public function set ($cellName, $cellValue): self {
+        $this->array[$cellName] = $cellValue;
         return $this;
     }
     /**
      * Remove a cell
      *
-     * @param mixed     $offset                      The cell offset
+     * @param mixed     $cellName                    The cell name/offset
      * @param bool|null $throwsForNonExistentElement If set, temporarily override {@see ImmutableArrayClass::$throwsForNonExistentElement}
      *
      * @return $this
      */
-    public function del ($offset, ?bool $throwsForNonExistentElement = null): self {
-        if ($throwsForNonExistentElement ?? $this->throwsForNonExistentElement() && !$this->has($offset)) {
+    public function del ($cellName, ?bool $throwsForNonExistentElement = null): self {
+        if ($throwsForNonExistentElement ?? $this->throwsForNonExistentElement() && !$this->has($cellName)) {
             throw new OutOfRangeException();
         }
-        unset($this->array[$offset]);
+        unset($this->array[$cellName]);
 
         return $this;
     }