diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9632954..b079a65 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -50,6 +50,7 @@ All Notable changes to `bakame/http-strucured-fields` will be documented in this
 - `Dictionary::toPairs` and `Parameters::toPairs`
 - `ByteSequence` class replaced by `Bytes` class
 - `DataType::create` method use a specific DataType class instead.
+- `Value` internal class.
 
 ## [1.3.0](https://github.com/bakame-php/http-structured-fields/compare/1.2.2...1.3.0) - 2024-01-05
 
diff --git a/phpstan.neon b/phpstan.neon
index 9d0a683..ee34f5f 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -11,7 +11,7 @@ parameters:
     ignoreErrors:
         - message: '#it_fails_to_create_an_item_from_an_array_of_pairs\(\)#'
           path: tests/ItemTest.php
-        - message: '#Method Bakame\\Http\\StructuredFields\\DataType::(serialize|build|create|toRfc9651|toRfc8941)\(\) has parameter \$data with no value type specified in iterable type iterable.#'
+        - message: '#Method Bakame\\Http\\StructuredFields\\DataType::(serialize|parse)\(\) has parameter \$data with no value type specified in iterable type iterable.#'
           path: src/DataType.php
     excludePaths:
         - tests/Record.php
diff --git a/src/DataType.php b/src/DataType.php
index b411039..8cc5f53 100644
--- a/src/DataType.php
+++ b/src/DataType.php
@@ -18,7 +18,7 @@ enum DataType: string
     /**
      * @throws SyntaxError|Exception
      */
-    public function parse(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651): OuterList|InnerList|Parameters|Dictionary|Item
+    public function parse(Stringable|string $httpValue, Ietf $rfc = Ietf::Rfc9651): OuterList|InnerList|Parameters|Dictionary|Item
     {
         return match ($this) {
             self::List => OuterList::fromHttpValue($httpValue, $rfc),
@@ -32,7 +32,7 @@ public function parse(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651):
     /**
      * @throws SyntaxError|Exception
      */
-    public function serialize(iterable $data, ?Ietf $rfc = Ietf::Rfc9651): string
+    public function serialize(iterable $data, Ietf $rfc = Ietf::Rfc9651): string
     {
         return (match ($this) {
             self::List => OuterList::fromPairs($data),
@@ -42,36 +42,4 @@ public function serialize(iterable $data, ?Ietf $rfc = Ietf::Rfc9651): string
             self::Parameters => Parameters::fromPairs($data),
         })->toHttpValue($rfc);
     }
-
-    /**
-     * @throws SyntaxError|Exception
-     */
-    public function fromRfc9651(Stringable|string $httpValue): OuterList|InnerList|Parameters|Dictionary|Item
-    {
-        return $this->parse($httpValue, Ietf::Rfc9651);
-    }
-
-    /**
-     * @throws SyntaxError|Exception
-     */
-    public function toRfc9651(iterable $data): string
-    {
-        return $this->serialize($data, Ietf::Rfc9651);
-    }
-
-    /**
-     * @throws SyntaxError|Exception
-     */
-    public function fromRfc8941(Stringable|string $httpValue): OuterList|InnerList|Parameters|Dictionary|Item
-    {
-        return $this->parse($httpValue, Ietf::Rfc8941);
-    }
-
-    /**
-     * @throws SyntaxError|Exception
-     */
-    public function toRfc8941(iterable $data): string
-    {
-        return $this->serialize($data, Ietf::Rfc8941);
-    }
 }
diff --git a/src/Dictionary.php b/src/Dictionary.php
index 28fb2be..5fcae80 100644
--- a/src/Dictionary.php
+++ b/src/Dictionary.php
@@ -14,14 +14,18 @@
 use Stringable;
 use Throwable;
 
+use function array_is_list;
 use function array_key_exists;
 use function array_keys;
+use function array_map;
 use function count;
 use function implode;
 use function is_array;
+use function is_bool;
 use function is_int;
 use function is_iterable;
 use function is_string;
+use function uasort;
 
 /**
  * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.2
@@ -56,14 +60,16 @@ private static function filterMember(mixed $member): InnerList|Item
     {
         if ($member instanceof StructuredFieldProvider) {
             $member = $member->toStructuredField();
+            if ($member instanceof Item || $member instanceof InnerList) {
+                return $member;
+            }
+
+            throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Item::class.' or an '.InnerList::class.'; '.$member::class.' given.');
         }
 
         return match (true) {
             $member instanceof InnerList,
             $member instanceof Item => $member,
-            $member instanceof OuterList,
-            $member instanceof Dictionary,
-            $member instanceof Parameters => throw new InvalidArgument('An instance of "'.$member::class.'" can not be a member of "'.self::class.'".'),
             is_iterable($member) => InnerList::new(...$member),
             default => Item::new($member),
         };
@@ -122,6 +128,11 @@ public static function fromPairs(StructuredFieldProvider|Dictionary|Parameters|i
         $converter = function (mixed $pair): InnerList|Item {
             if ($pair instanceof StructuredFieldProvider) {
                 $pair = $pair->toStructuredField();
+                if ($pair instanceof Item || $pair instanceof InnerList) {
+                    return $pair;
+                }
+
+                throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Item::class.' or an '.InnerList::class.'; '.$pair::class.' given.');
             }
 
             if ($pair instanceof InnerList || $pair instanceof Item) {
@@ -140,13 +151,11 @@ public static function fromPairs(StructuredFieldProvider|Dictionary|Parameters|i
                 return InnerList::new();
             }
 
-            [$member, $parameters] = match (count($pair)) {
-                2 => $pair,
-                1 => [$pair[0], []],
-                default => throw new SyntaxError('The pair first member is the item value; its second member is the item parameters.'),
-            };
+            if (!in_array(count($pair), [1, 2], true)) {
+                throw new SyntaxError('The pair first member is the item value; its second member is the item parameters.');
+            }
 
-            return is_iterable($member) ? InnerList::fromPair([$member, $parameters]) : Item::fromPair([$member, $parameters]);
+            return is_iterable($pair[0]) ? InnerList::fromPair($pair) : Item::fromPair($pair);
         };
 
         return match (true) {
@@ -191,9 +200,9 @@ public static function fromRfc8941(Stringable|string $httpValue): self
      *
      * @throws StructuredFieldError|Throwable If the string is not a valid
      */
-    public static function fromHttpValue(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651): self
+    public static function fromHttpValue(Stringable|string $httpValue, Ietf $rfc = Ietf::Rfc9651): self
     {
-        return self::fromPairs(Parser::new($rfc)->parseDictionary($httpValue)); /* @phpstan-ignore-line */
+        return self::fromPairs((new Parser($rfc))->parseDictionary($httpValue)); /* @phpstan-ignore-line */
     }
 
     public function toRfc9651(): string
@@ -206,18 +215,14 @@ public function toRfc8941(): string
         return $this->toHttpValue(Ietf::Rfc8941);
     }
 
-    public function toHttpValue(?Ietf $rfc = Ietf::Rfc9651): string
+    public function toHttpValue(Ietf $rfc = Ietf::Rfc9651): string
     {
-        $rfc ??= Ietf::Rfc9651;
-        $members = [];
-        foreach ($this->members as $key => $member) {
-            $members[] = match (true) {
-                $member instanceof Item && true === $member->value() => $key.$member->parameters()->toHttpValue($rfc),
-                default => $key.'='.$member->toHttpValue($rfc),
-            };
-        }
+        $formatter = static fn (Item|InnerList $member, string $offset): string => match (true) {
+            $member instanceof Item && true === $member->value() => $offset.$member->parameters()->toHttpValue($rfc),
+            default => $offset.'='.$member->toHttpValue($rfc),
+        };
 
-        return implode(', ', $members);
+        return implode(', ', array_map($formatter, $this->members, array_keys($this->members)));
     }
 
     public function __toString(): string
@@ -506,7 +511,7 @@ public function last(): array
      */
     public function add(
         string $key,
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool|null $member
+        iterable|StructuredFieldProvider|Dictionary|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool|null $member
     ): self {
         if (null === $member) {
             return $this;
@@ -596,7 +601,7 @@ public function removeByKeys(string ...$keys): self
      */
     public function append(
         string $key,
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
+        iterable|StructuredFieldProvider|Dictionary|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): self {
         $members = $this->members;
         unset($members[$key]);
@@ -616,7 +621,7 @@ public function append(
      */
     public function prepend(
         string $key,
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
+        iterable|StructuredFieldProvider|Dictionary|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): self {
         $members = $this->members;
         unset($members[$key]);
@@ -840,7 +845,7 @@ public function filter(callable $callback): self
     public function sort(callable $callback): self
     {
         $members = iterator_to_array($this);
-        usort($members, $callback);
+        uasort($members, $callback);
 
         return self::fromPairs($members);
     }
diff --git a/src/DisplayString.php b/src/DisplayString.php
index 741391d..361f91e 100644
--- a/src/DisplayString.php
+++ b/src/DisplayString.php
@@ -11,6 +11,7 @@
 use function preg_replace_callback;
 use function rawurldecode;
 use function rawurlencode;
+use function str_contains;
 
 /**
  * @see https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-sfbis#section-4.2.10
diff --git a/src/InnerList.php b/src/InnerList.php
index 8c302d7..00d5675 100644
--- a/src/InnerList.php
+++ b/src/InnerList.php
@@ -20,6 +20,7 @@
 use function array_values;
 use function count;
 use function implode;
+use function uasort;
 
 use const ARRAY_FILTER_USE_BOTH;
 use const ARRAY_FILTER_USE_KEY;
@@ -46,10 +47,10 @@ final class InnerList implements ArrayAccess, Countable, IteratorAggregate
     /**
      * @param iterable<SfItemInput> $members
      */
-    private function __construct(iterable $members, Parameters $parameters)
+    private function __construct(iterable $members, ?Parameters $parameters = null)
     {
         $this->members = array_map($this->filterMember(...), array_values([...$members]));
-        $this->parameters = $parameters;
+        $this->parameters = $parameters ?? Parameters::new();
     }
 
     /**
@@ -59,12 +60,18 @@ private function filterMember(mixed $member): Item
     {
         if ($member instanceof StructuredFieldProvider) {
             $member = $member->toStructuredField();
+            if (!$member instanceof Item) {
+                throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Item::class.'; '.$member::class.' given.');
+            }
+
+            return $member;
         }
 
-        return match (true) {
-            $member instanceof Item => $member,
-            default => Item::new($member),
-        };
+        if (!$member instanceof Item) {
+            return Item::new($member);
+        }
+
+        return $member;
     }
 
     /**
@@ -72,9 +79,9 @@ private function filterMember(mixed $member): Item
      *
      * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.1
      */
-    public static function fromHttpValue(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651): self
+    public static function fromHttpValue(Stringable|string $httpValue, Ietf $rfc = Ietf::Rfc9651): self
     {
-        return self::fromPair(Parser::new($rfc)->parseInnerList($httpValue));
+        return self::fromPair((new Parser($rfc))->parseInnerList($httpValue));
     }
 
     /**
@@ -95,7 +102,7 @@ public static function fromAssociative(
         }
 
         if (!$parameters instanceof Parameters) {
-            $parameters = Parameters::fromAssociative($parameters);
+            return new self($value, Parameters::fromAssociative($parameters));
         }
 
         return new self($value, $parameters);
@@ -115,7 +122,7 @@ public static function fromPair(array $pair): self
         }
 
         if (1 === count($pair)) {
-            return new self($pair[0], Parameters::new());
+            return new self($pair[0]);
         }
 
         if ($pair[1] instanceof StructuredFieldProvider) {
@@ -126,7 +133,7 @@ public static function fromPair(array $pair): self
         }
 
         if (!$pair[1] instanceof Parameters) {
-            $pair[1] = Parameters::fromPairs($pair[1]);
+            return new self($pair[0], Parameters::fromPairs($pair[1]));
         }
 
         return new self($pair[0], $pair[1]);
@@ -138,7 +145,7 @@ public static function fromPair(array $pair): self
     public static function new(
         StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
     ): self {
-        return new self($members, Parameters::new());
+        return new self($members);
     }
 
     public static function fromRfc9651(Stringable|string $httpValue): self
@@ -151,10 +158,8 @@ public static function fromRfc8941(Stringable|string $httpValue): self
         return self::fromHttpValue($httpValue, Ietf::Rfc8941);
     }
 
-    public function toHttpValue(?Ietf $rfc = Ietf::Rfc9651): string
+    public function toHttpValue(Ietf $rfc = Ietf::Rfc9651): string
     {
-        $rfc ??= Ietf::Rfc9651;
-
         return '('.implode(' ', array_map(fn (Item $value): string => $value->toHttpValue($rfc), $this->members)).')'.$this->parameters->toHttpValue($rfc);
     }
 
@@ -483,7 +488,7 @@ public function filter(callable $callback): self
     public function sort(callable $callback): self
     {
         $members = $this->members;
-        usort($members, $callback);
+        uasort($members, $callback);
 
         return new self($members, $this->parameters);
     }
diff --git a/src/Item.php b/src/Item.php
index af969df..67f2698 100644
--- a/src/Item.php
+++ b/src/Item.php
@@ -8,11 +8,16 @@
 use DateTimeImmutable;
 use DateTimeInterface;
 use DateTimeZone;
+use Exception;
 use Stringable;
+use Throwable;
 
 use function array_is_list;
 use function count;
 
+use const JSON_PRESERVE_ZERO_FRACTION;
+use const PHP_ROUND_HALF_EVEN;
+
 /**
  * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.3
  *
@@ -25,8 +30,19 @@ final class Item
 {
     use ParameterAccess;
 
-    private function __construct(private readonly Value $value, private readonly Parameters $parameters)
+    private readonly Token|Bytes|DisplayString|DateTimeImmutable|int|float|string|bool $value;
+    private readonly Parameters $parameters;
+    private readonly Type $type;
+
+    private function __construct(Token|Bytes|DisplayString|DateTimeInterface|int|float|string|bool $value, ?Parameters $parameters = null)
     {
+        if ($value instanceof DateTimeInterface && !$value instanceof DateTimeImmutable) {
+            $value = DateTimeImmutable::createFromInterface($value);
+        }
+
+        $this->value = $value;
+        $this->parameters = $parameters ?? Parameters::new();
+        $this->type = Type::fromVariable($value);
     }
 
     public static function fromRfc9651(Stringable|string $httpValue): self
@@ -45,11 +61,11 @@ public static function fromRfc8941(Stringable|string $httpValue): self
      *
      * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.3
      *
-     * @throws SyntaxError If the HTTP value can not be parsed
+     * @throws SyntaxError|Exception If the HTTP value can not be parsed
      */
-    public static function fromHttpValue(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651): self
+    public static function fromHttpValue(Stringable|string $httpValue, Ietf $rfc = Ietf::Rfc9651): self
     {
-        return self::fromPair(Parser::new($rfc)->parseItem($httpValue));
+        return self::fromPair((new Parser($rfc))->parseItem($httpValue));
     }
 
     /**
@@ -65,16 +81,18 @@ public static function fromAssociative(
     ): self {
         if ($parameters instanceof StructuredFieldProvider) {
             $parameters = $parameters->toStructuredField();
-            if (!$parameters instanceof Parameters) {
-                throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Parameters::class.'; '.$parameters::class.' given.');
+            if ($parameters instanceof Parameters) {
+                return new self($value, $parameters);
             }
+
+            throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Parameters::class.'; '.$parameters::class.' given.');
         }
 
         if (!$parameters instanceof Parameters) {
-            $parameters = Parameters::fromAssociative($parameters);
+            return new self($value, Parameters::fromAssociative($parameters));
         }
 
-        return new self(new Value($value), $parameters);
+        return new self($value, $parameters);
     }
 
     /**
@@ -97,22 +115,27 @@ public static function tryFromPair(array $pair): ?self
     public static function fromPair(array $pair): self
     {
         if ([] === $pair || !array_is_list($pair) || 2 < count($pair)) {
-            throw new SyntaxError('The pair must be represented by an non-empty array as a list containing at most 2 members.');
+            throw new SyntaxError('The pair must be represented by an non-empty array as a list containing exactly 1 or 2 members.');
         }
 
         if (1 === count($pair)) {
-            return new self(new Value($pair[0]), Parameters::new());
+            return new self($pair[0]);
         }
 
         if ($pair[1] instanceof StructuredFieldProvider) {
             $pair[1] = $pair[1]->toStructuredField();
+            if ($pair[1] instanceof Parameters) {
+                return new self($pair[0], Parameters::fromPairs($pair[1]));
+            }
+
+            throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Parameters::class.'; '.$pair[1]::class.' given.');
         }
 
         if (!$pair[1] instanceof Parameters) {
-            $pair[1] = Parameters::fromPairs($pair[1]);
+            return new self($pair[0], Parameters::fromPairs($pair[1]));
         }
 
-        return new self(new Value($pair[0]), $pair[1]);
+        return new self($pair[0], $pair[1]);
     }
 
     /**
@@ -125,14 +148,14 @@ public static function fromPair(array $pair): self
     public static function new(mixed $value): self
     {
         if ($value instanceof Item) {
-            return new self(new Value($value->value()), $value->parameters());
+            return new self($value->value(), $value->parameters());
         }
 
         if (is_array($value)) {
             return self::fromPair($value);
         }
 
-        return self::fromValue(new Value($value)); /* @phpstan-ignore-line */
+        return new self($value); /* @phpstan-ignore-line */
     }
 
     /**
@@ -140,7 +163,7 @@ public static function new(mixed $value): self
      *
      * @param SfTypeInput|Item|array{0:SfTypeInput, 1:Parameters|iterable<array{0:string, 1:SfTypeInput}>} $value
      */
-    public static function tryNew(StructuredFieldProvider|Item|DateTimeInterface|Bytes|DisplayString|Token|array|int|float|string|bool  $value): ?self
+    public static function tryNew(StructuredFieldProvider|Item|DateTimeInterface|Bytes|DisplayString|Token|array|int|float|string|bool $value): ?self
     {
         try {
             return self::new($value);
@@ -149,14 +172,6 @@ public static function tryNew(StructuredFieldProvider|Item|DateTimeInterface|Byt
         }
     }
 
-    /**
-     * Returns a new bare instance from value.
-     */
-    private static function fromValue(Value $value): self
-    {
-        return new self($value, Parameters::new());
-    }
-
     /**
      * Returns a new instance from a string.
      *
@@ -164,7 +179,7 @@ private static function fromValue(Value $value): self
      */
     public static function fromString(Stringable|string $value): self
     {
-        return self::fromValue(Value::fromString($value));
+        return new self((string)$value);
     }
 
     /**
@@ -174,7 +189,7 @@ public static function fromString(Stringable|string $value): self
      */
     public static function fromEncodedBytes(Stringable|string $value): self
     {
-        return self::fromValue(Value::fromEncodedBytes($value));
+        return new self(Bytes::fromEncoded($value));
     }
 
     /**
@@ -184,7 +199,7 @@ public static function fromEncodedBytes(Stringable|string $value): self
      */
     public static function fromDecodedBytes(Stringable|string $value): self
     {
-        return self::fromValue(Value::fromDecodedBytes($value));
+        return new self(Bytes::fromDecoded($value));
     }
 
     /**
@@ -194,7 +209,7 @@ public static function fromDecodedBytes(Stringable|string $value): self
      */
     public static function fromEncodedDisplayString(Stringable|string $value): self
     {
-        return self::fromValue(Value::fromEncodedDisplayString($value));
+        return new self(DisplayString::fromEncoded($value));
     }
 
     /**
@@ -204,7 +219,7 @@ public static function fromEncodedDisplayString(Stringable|string $value): self
      */
     public static function fromDecodedDisplayString(Stringable|string $value): self
     {
-        return self::fromValue(Value::fromDecodedDisplayString($value));
+        return new self(DisplayString::fromDecoded($value));
     }
 
     /**
@@ -214,7 +229,7 @@ public static function fromDecodedDisplayString(Stringable|string $value): self
      */
     public static function fromToken(Stringable|string $value): self
     {
-        return self::fromValue(Value::fromToken($value));
+        return new self(Token::fromString($value));
     }
 
     /**
@@ -224,7 +239,7 @@ public static function fromToken(Stringable|string $value): self
      */
     public static function fromTimestamp(int $timestamp): self
     {
-        return self::fromValue(Value::fromTimestamp($timestamp));
+        return new self((new DateTimeImmutable())->setTimestamp($timestamp));
     }
 
     /**
@@ -234,7 +249,17 @@ public static function fromTimestamp(int $timestamp): self
      */
     public static function fromDateFormat(string $format, string $datetime): self
     {
-        return self::fromValue(Value::fromDateFormat($format, $datetime));
+        try {
+            $value = DateTimeImmutable::createFromFormat($format, $datetime);
+        } catch (Exception $exception) {
+            throw new SyntaxError('The date notation `'.$datetime.'` is incompatible with the date format `'.$format.'`.', 0, $exception);
+        }
+
+        if (!$value instanceof DateTimeImmutable) {
+            throw new SyntaxError('The date notation `'.$datetime.'` is incompatible with the date format `'.$format.'`.');
+        }
+
+        return new self($value);
     }
 
     /**
@@ -244,7 +269,20 @@ public static function fromDateFormat(string $format, string $datetime): self
      */
     public static function fromDateString(string $datetime, DateTimeZone|string|null $timezone = null): self
     {
-        return self::fromValue(Value::fromDateString($datetime, $timezone));
+        $timezone ??= date_default_timezone_get();
+        if (!$timezone instanceof DateTimeZone) {
+            try {
+                $timezone = new DateTimeZone($timezone);
+            } catch (Throwable $exception) {
+                throw new SyntaxError('The timezone could not be instantiated.', 0, $exception);
+            }
+        }
+
+        try {
+            return new self(new DateTimeImmutable($datetime, $timezone));
+        } catch (Throwable $exception) {
+            throw new SyntaxError('Unable to create a '.DateTimeImmutable::class.' instance with the date notation `'.$datetime.'.`', 0, $exception);
+        }
     }
 
     /**
@@ -254,7 +292,7 @@ public static function fromDateString(string $datetime, DateTimeZone|string|null
      */
     public static function fromDate(DateTimeInterface $datetime): self
     {
-        return self::fromValue(Value::fromDate($datetime));
+        return new self($datetime);
     }
 
     /**
@@ -264,7 +302,7 @@ public static function fromDate(DateTimeInterface $datetime): self
      */
     public static function fromDecimal(int|float $value): self
     {
-        return self::fromValue(Value::fromDecimal($value));
+        return new self((float)$value);
     }
 
     /**
@@ -274,7 +312,7 @@ public static function fromDecimal(int|float $value): self
      */
     public static function fromInteger(int|float $value): self
     {
-        return self::fromValue(Value::fromInteger($value));
+        return new self((int)$value);
     }
 
     /**
@@ -282,7 +320,7 @@ public static function fromInteger(int|float $value): self
      */
     public static function true(): self
     {
-        return self::fromValue(Value::true());
+        return new self(true);
     }
 
     /**
@@ -290,7 +328,7 @@ public static function true(): self
      */
     public static function false(): self
     {
-        return self::fromValue(Value::false());
+        return new self(false);
     }
 
     /**
@@ -306,26 +344,25 @@ public static function false(): self
      */
     public function value(?callable $validate = null): Bytes|Token|DisplayString|DateTimeImmutable|string|int|float|bool
     {
-        $value = $this->value->value;
         if (null === $validate) {
-            return $value;
+            return $this->value;
         }
 
-        $exceptionMessage = $validate($value);
+        $exceptionMessage = $validate($this->value);
         if (true === $exceptionMessage) {
-            return $value;
+            return $this->value;
         }
 
         if (!is_string($exceptionMessage) || '' === trim($exceptionMessage)) {
             $exceptionMessage = "The item value '{value}' failed validation.";
         }
 
-        throw new Violation(strtr($exceptionMessage, ['{value}' => $this->value->serialize()]));
+        throw new Violation(strtr($exceptionMessage, ['{value}' => $this->serialize()]));
     }
 
     public function type(): Type
     {
-        return $this->value->type;
+        return $this->type;
     }
 
     /**
@@ -333,11 +370,30 @@ public function type(): Type
      *
      * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-4.1
      */
-    public function toHttpValue(?Ietf $rfc = Ietf::Rfc9651): string
+    public function toHttpValue(Ietf $rfc = Ietf::Rfc9651): string
     {
-        $rfc ??= Ietf::Rfc9651;
+        return $this->serialize($rfc).$this->parameters->toHttpValue($rfc);
+    }
 
-        return $this->value->serialize($rfc).$this->parameters->toHttpValue($rfc);
+    /**
+     * Serialize the Item value according to RFC8941.
+     *
+     * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-4.1
+     */
+    private function serialize(Ietf $rfc = Ietf::Rfc9651): string
+    {
+        return match (true) {
+            !$rfc->supports($this->type) => throw MissingFeature::dueToLackOfSupport($this->type, $rfc),
+            $this->value instanceof DateTimeImmutable => '@'.$this->value->getTimestamp(),
+            $this->value instanceof Token => $this->value->toString(),
+            $this->value instanceof Bytes => ':'.$this->value->encoded().':',
+            $this->value instanceof DisplayString => '%"'.$this->value->encoded().'"',
+            is_int($this->value) => (string)$this->value,
+            is_float($this->value) => (string)json_encode(round($this->value, 3, PHP_ROUND_HALF_EVEN), JSON_PRESERVE_ZERO_FRACTION),
+            $this->value,
+            false === $this->value => '?'.($this->value ? '1' : '0'),
+            default => '"'.preg_replace('/(["\\\])/', '\\\$1', $this->value).'"',
+        };
     }
 
     public function toRfc9651(): string
@@ -360,7 +416,7 @@ public function __toString(): string
      */
     public function toPair(): array
     {
-        return [$this->value->value, $this->parameters];
+        return [$this->value, $this->parameters];
     }
 
     public function equals(mixed $other): bool
@@ -396,11 +452,17 @@ public function when(callable|bool $condition, callable $onSuccess, ?callable $o
      *
      * @throws SyntaxError If the value is invalid or not supported
      */
-    public function withValue(
-        DateTimeInterface|Bytes|Token|DisplayString|string|int|float|bool $value
-    ): self {
-        $value = new Value($value);
-        if ($value->equals($this->value)) {
+    public function withValue(DateTimeInterface|Bytes|Token|DisplayString|string|int|float|bool $value): self
+    {
+        $isEqual = match (true) {
+            $this->value instanceof Bytes,
+            $this->value instanceof Token,
+            $this->value instanceof DisplayString => $this->value->equals($value),
+            $this->value instanceof DateTimeInterface && $value instanceof DateTimeInterface => $value == $this->value,
+            default => $value === $this->value,
+        };
+
+        if ($isEqual) {
             return $this;
         }
 
diff --git a/src/OuterList.php b/src/OuterList.php
index c6fcad1..c3a970b 100644
--- a/src/OuterList.php
+++ b/src/OuterList.php
@@ -22,6 +22,7 @@
 use function implode;
 use function is_array;
 use function is_iterable;
+use function uasort;
 
 use const ARRAY_FILTER_USE_BOTH;
 use const ARRAY_FILTER_USE_KEY;
@@ -45,7 +46,7 @@ final class OuterList implements ArrayAccess, Countable, IteratorAggregate
      * @param SfMemberInput ...$members
      */
     private function __construct(
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
+        iterable|StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
     ) {
         $this->members = array_map($this->filterMember(...), array_values([...$members]));
     }
@@ -57,14 +58,16 @@ private function filterMember(mixed $member): InnerList|Item
     {
         if ($member instanceof StructuredFieldProvider) {
             $member = $member->toStructuredField();
+            if ($member instanceof Item || $member instanceof InnerList) {
+                return $member;
+            }
+
+            throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Item::class.' or an '.InnerList::class.'; '.$member::class.' given.');
         }
 
         return match (true) {
             $member instanceof InnerList,
             $member instanceof Item => $member,
-            $member instanceof OuterList,
-            $member instanceof Parameters,
-            $member instanceof Dictionary => throw new InvalidArgument('An instance of "'.$member::class.'" can not be a member of "'.self::class.'".'),
             is_iterable($member) => InnerList::new(...$member),
             default => Item::new($member),
         };
@@ -75,9 +78,9 @@ private function filterMember(mixed $member): InnerList|Item
      *
      * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.1
      */
-    public static function fromHttpValue(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651): self
+    public static function fromHttpValue(Stringable|string $httpValue, Ietf $rfc = Ietf::Rfc9651): self
     {
-        return self::fromPairs(Parser::new($rfc)->parseList($httpValue)); /* @phpstan-ignore-line */
+        return self::fromPairs((new Parser($rfc))->parseList($httpValue)); /* @phpstan-ignore-line */
     }
 
     /**
@@ -96,6 +99,11 @@ public static function fromPairs(StructuredFieldProvider|iterable $pairs): self
         $converter = function (mixed $pair): InnerList|Item {
             if ($pair instanceof StructuredFieldProvider) {
                 $pair = $pair->toStructuredField();
+                if ($pair instanceof Item || $pair instanceof InnerList) {
+                    return $pair;
+                }
+
+                throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Item::class.' or an '.InnerList::class.'; '.$pair::class.' given.');
             }
 
             if ($pair instanceof InnerList || $pair instanceof Item) {
@@ -114,13 +122,11 @@ public static function fromPairs(StructuredFieldProvider|iterable $pairs): self
                 return InnerList::new();
             }
 
-            [$member, $parameters] = match (count($pair)) {
-                2 => $pair,
-                1 => [$pair[0], []],
-                default => throw new SyntaxError('The pair first member is the item value; its second member is the item parameters.'),
-            };
+            if (!in_array(count($pair), [1, 2], true)) {
+                throw new SyntaxError('The pair first member is the item value; its second member is the item parameters.');
+            }
 
-            return is_iterable($member) ? InnerList::fromPair([$member, $parameters]) : Item::fromPair([$member, $parameters]);
+            return is_iterable($pair[0]) ? InnerList::fromPair($pair) : Item::fromPair($pair);
         };
 
         return match (true) {
@@ -137,7 +143,7 @@ public static function fromPairs(StructuredFieldProvider|iterable $pairs): self
     /**
      * @param SfMemberInput ...$members
      */
-    public static function new(iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members): self
+    public static function new(iterable|StructuredFieldProvider|InnerList|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members): self
     {
         return new self(...$members);
     }
@@ -152,10 +158,8 @@ public static function fromRfc8941(Stringable|string $httpValue): self
         return self::fromHttpValue($httpValue, Ietf::Rfc8941);
     }
 
-    public function toHttpValue(?Ietf $rfc = Ietf::Rfc9651): string
+    public function toHttpValue(Ietf $rfc = Ietf::Rfc9651): string
     {
-        $rfc ??= Ietf::Rfc9651;
-
         return implode(', ', array_map(fn (Item|InnerList $member): string => $member->toHttpValue($rfc), $this->members));
     }
 
@@ -291,7 +295,7 @@ public function last(): InnerList|Item|null
      * @param SfMemberInput ...$members
      */
     public function unshift(
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|iterable|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
+        StructuredFieldProvider|InnerList|Item|iterable|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
     ): self {
         $membersToAdd = array_reduce(
             $members,
@@ -317,7 +321,7 @@ function (array $carry, $member) {
      * @param SfMemberInput ...$members
      */
     public function push(
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
+        iterable|StructuredFieldProvider|InnerList|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
     ): self {
         $membersToAdd = array_reduce(
             $members,
@@ -346,7 +350,7 @@ function (array $carry, $member) {
      */
     public function insert(
         int $index,
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
+        iterable|StructuredFieldProvider|InnerList|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool ...$members
     ): self {
         $offset = $this->filterIndex($index) ?? throw InvalidOffset::dueToIndexNotFound($index);
 
@@ -367,7 +371,7 @@ public function insert(
      */
     public function replace(
         int $index,
-        iterable|StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
+        iterable|StructuredFieldProvider|InnerList|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): self {
         $offset = $this->filterIndex($index) ?? throw InvalidOffset::dueToIndexNotFound($index);
         $member = self::filterMember($member);
@@ -473,7 +477,7 @@ public function filter(callable $callback): self
     public function sort(callable $callback): self
     {
         $members = $this->members;
-        usort($members, $callback);
+        uasort($members, $callback);
 
         return new self(...$members);
     }
diff --git a/src/ParameterAccess.php b/src/ParameterAccess.php
index 5750126..9c71f09 100644
--- a/src/ParameterAccess.php
+++ b/src/ParameterAccess.php
@@ -76,13 +76,13 @@ abstract public function withParameters(Parameters $parameters): static;
      * This method MUST retain the state of the current instance, and return
      * an instance that contains the specified parameter change.
      *
-     * @param StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|SfType|null $member
+     * @param StructuredFieldProvider|Item|SfType $member
      *
      * @throws SyntaxError If the string key is not a valid
      */
     public function addParameter(
         string $key,
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool|null $member
+        StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): static {
         return $this->withParameters($this->parameters()->add($key, $member));
     }
@@ -93,13 +93,13 @@ public function addParameter(
      * This method MUST retain the state of the current instance, and return
      * an instance that contains the specified parameter change.
      *
-     * @param StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|SfType $member
+     * @param StructuredFieldProvider|Item|SfType $member
      *
      * @throws SyntaxError If the string key is not a valid
      */
     public function prependParameter(
         string $key,
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool  $member
+        StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool  $member
     ): static {
         return $this->withParameters($this->parameters()->prepend($key, $member));
     }
@@ -110,13 +110,13 @@ public function prependParameter(
      * This method MUST retain the state of the current instance, and return
      * an instance that contains the specified parameter change.
      *
-     * @param StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|SfType $member
+     * @param StructuredFieldProvider|Item|SfType $member
      *
      * @throws SyntaxError If the string key is not a valid
      */
     public function appendParameter(
         string $key,
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
+        StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): static {
         return $this->withParameters($this->parameters()->append($key, $member));
     }
diff --git a/src/Parameters.php b/src/Parameters.php
index a10c2cf..9ad342f 100644
--- a/src/Parameters.php
+++ b/src/Parameters.php
@@ -22,6 +22,7 @@
 use function implode;
 use function is_int;
 use function is_string;
+use function uasort;
 
 /**
  * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.1.2
@@ -29,7 +30,7 @@
  * @phpstan-import-type SfItemInput from StructuredFieldProvider
  * @phpstan-import-type SfType from StructuredFieldProvider
  *
- * @implements ArrayAccess<string, InnerList|Item>
+ * @implements ArrayAccess<string, Item>
  * @implements IteratorAggregate<int, array{0:string, 1:Item}>
  */
 final class Parameters implements ArrayAccess, Countable, IteratorAggregate
@@ -57,13 +58,22 @@ private static function filterMember(mixed $member): Item
     {
         if ($member instanceof StructuredFieldProvider) {
             $member = $member->toStructuredField();
+            if ($member instanceof Item) {
+                return self::filterMember($member);
+            }
+
+            throw new InvalidArgument('The '.StructuredFieldProvider::class.' must provide a '.Item::class.'; '.$member::class.' given.');
         }
 
-        return match (true) {
-            !$member instanceof Item => Item::new($member),
-            $member->parameters()->isEmpty() => $member,
-            default => throw new InvalidArgument('The "'.$member::class.'" instance is not a Bare Item.'),
-        };
+        if (!$member instanceof Item) {
+            $member = Item::new($member);
+        }
+
+        if ($member->parameters()->isNotEmpty()) {
+            throw new InvalidArgument('The "'.$member::class.'" instance is not a Bare Item.');
+        }
+
+        return $member;
     }
 
     /**
@@ -134,9 +144,9 @@ public static function fromPairs(StructuredFieldProvider|iterable $pairs): self
      *
      * @throws SyntaxError|Exception If the string is not a valid
      */
-    public static function fromHttpValue(Stringable|string $httpValue, ?Ietf $rfc = Ietf::Rfc9651): self
+    public static function fromHttpValue(Stringable|string $httpValue, Ietf $rfc = Ietf::Rfc9651): self
     {
-        return self::fromPairs(Parser::new($rfc)->parseParameters($httpValue)); /* @phpstan-ignore-line */
+        return self::fromPairs((new Parser($rfc))->parseParameters($httpValue)); /* @phpstan-ignore-line */
     }
 
     public static function fromRfc9651(Stringable|string $httpValue): self
@@ -149,9 +159,8 @@ public static function fromRfc8941(Stringable|string $httpValue): self
         return self::fromHttpValue($httpValue, Ietf::Rfc8941);
     }
 
-    public function toHttpValue(?Ietf $rfc = Ietf::Rfc9651): string
+    public function toHttpValue(Ietf $rfc = Ietf::Rfc9651): string
     {
-        $rfc ??= Ietf::Rfc9651;
         $formatter = static fn (Item $member, string $offset): string => match (true) {
             true === $member->value() => ';'.$offset,
             default => ';'.$offset.'='.$member->toHttpValue($rfc),
@@ -497,15 +506,12 @@ public function valueByIndex(int $index, ?callable $validate = null, bool|string
     }
 
     /**
-     * @param StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|SfType|null $member
+     * @param StructuredFieldProvider|Item|SfType $member
      */
     public function add(
         string $key,
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool|null $member
+        StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): self {
-        if (null === $member) {
-            return $this;
-        }
         $members = $this->members;
         $members[MapKey::from($key)->value] = self::filterMember($member);
 
@@ -563,11 +569,11 @@ public function removeByKeys(string ...$keys): self
     }
 
     /**
-     * @param StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|SfType $member
+     * @param StructuredFieldProvider|Item|SfType $member
      */
     public function append(
         string $key,
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
+        StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): self {
         $members = $this->members;
         unset($members[$key]);
@@ -576,11 +582,11 @@ public function append(
     }
 
     /**
-     * @param StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|SfType $member
+     * @param StructuredFieldProvider|Item|SfType $member
      */
     public function prepend(
         string $key,
-        StructuredFieldProvider|OuterList|Dictionary|InnerList|Parameters|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
+        StructuredFieldProvider|Item|Token|Bytes|DisplayString|DateTimeInterface|string|int|float|bool $member
     ): self {
         $members = $this->members;
         unset($members[$key]);
diff --git a/src/Parser.php b/src/Parser.php
index 3b38e0e..e57ce87 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -14,6 +14,7 @@
 use function str_contains;
 use function strlen;
 use function substr;
+use function trim;
 
 /**
  * A class to parse HTTP Structured Fields from their HTTP textual representation according to RFC8941.
@@ -52,11 +53,6 @@ final class Parser
     private const FIRST_CHARACTER_RANGE_NUMBER = '-1234567890';
     private const FIRST_CHARACTER_RANGE_TOKEN = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ*';
 
-    public static function new(?Ietf $rfc = Ietf::Rfc9651): self
-    {
-        return new self($rfc ?? Ietf::Rfc9651);
-    }
-
     public function __construct(private readonly Ietf $rfc)
     {
     }
@@ -518,10 +514,10 @@ private static function extractToken(string $httpValue): array
      */
     private static function extractBytes(string $httpValue): array
     {
-        if (1 !== preg_match(self::REGEXP_BYTES, $httpValue, $matches)) {
+        if (1 !== preg_match(self::REGEXP_BYTES, $httpValue, $found)) {
             throw new SyntaxError("The HTTP textual representation \"$httpValue\" for a Byte Sequence contains invalid characters.");
         }
 
-        return [Bytes::fromEncoded($matches['byte']), strlen($matches['sequence'])];
+        return [Bytes::fromEncoded($found['byte']), strlen($found['sequence'])];
     }
 }
diff --git a/src/Token.php b/src/Token.php
index 407d26f..88f41db 100644
--- a/src/Token.php
+++ b/src/Token.php
@@ -37,7 +37,7 @@ public static function tryFromString(Stringable|string $value): ?self
 
     public static function fromString(Stringable|string $value): self
     {
-        return new self((string) $value);
+        return new self((string)$value);
     }
 
     public function equals(mixed $other): bool
diff --git a/src/Type.php b/src/Type.php
index 112d87a..44eb876 100644
--- a/src/Type.php
+++ b/src/Type.php
@@ -6,6 +6,15 @@
 
 use DateTimeInterface;
 
+use function abs;
+use function floor;
+use function gettype;
+use function is_float;
+use function is_int;
+use function is_object;
+use function is_string;
+use function preg_match;
+
 /**
  * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.3
  */
diff --git a/src/Value.php b/src/Value.php
deleted file mode 100644
index e2b409c..0000000
--- a/src/Value.php
+++ /dev/null
@@ -1,224 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Bakame\Http\StructuredFields;
-
-use DateTimeImmutable;
-use DateTimeInterface;
-use DateTimeZone;
-use Exception;
-use Stringable;
-use Throwable;
-
-use function date_default_timezone_get;
-use function is_float;
-use function is_int;
-use function json_encode;
-use function preg_replace;
-use function round;
-
-use const JSON_PRESERVE_ZERO_FRACTION;
-use const PHP_ROUND_HALF_EVEN;
-
-/**
- * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-3.3
- * @internal
- */
-final class Value
-{
-    public readonly Token|Bytes|DisplayString|DateTimeImmutable|int|float|string|bool $value;
-    public readonly Type $type;
-
-    /**
-     * @throws SyntaxError
-     */
-    public function __construct(Item|Token|Bytes|DisplayString|DateTimeInterface|int|float|string|bool $value)
-    {
-        [$this->value, $this->type] = match (true) {
-            $value instanceof Item => [$value->value(), $value->type()],
-            $value instanceof Token,
-            $value instanceof Bytes,
-            $value instanceof DisplayString => [$value, $value->type()],
-            false === $value,
-            $value => [$value, Type::Boolean],
-            $value instanceof DateTimeInterface => [self::filterDate($value), Type::Date],
-            default => [$value, Type::fromVariable($value)],
-        };
-    }
-
-    /**
-     * Filter a date according to draft-ietf-httpbis-sfbis-latest.
-     *
-     * @see https://httpwg.org/http-extensions/draft-ietf-httpbis-sfbis.html#section-3.3.7
-     */
-    private static function filterDate(DateTimeInterface $value): DateTimeImmutable
-    {
-        return match (true) {
-            !Type::Integer->supports($value->getTimestamp()) => throw new SyntaxError('Date timestamp are limited to 15 digits.'),
-            !$value instanceof DateTimeImmutable => DateTimeImmutable::createFromInterface($value),
-            default => $value,
-        };
-    }
-
-    /**
-     * Returns a new instance from an encoded byte sequence and an iterable of key-value parameters.
-     */
-    public static function fromEncodedBytes(Stringable|string $value): self
-    {
-        return new self(Bytes::fromEncoded($value));
-    }
-
-    /**
-     * Returns a new instance from a decoded byte sequence and an iterable of key-value parameters.
-     */
-    public static function fromDecodedBytes(Stringable|string $value): self
-    {
-        return new self(Bytes::fromDecoded($value));
-    }
-
-    public static function fromEncodedDisplayString(Stringable|string $value): self
-    {
-        return new self(DisplayString::fromEncoded($value));
-    }
-
-    public static function fromDecodedDisplayString(Stringable|string $value): self
-    {
-        return new self(DisplayString::fromDecoded($value));
-    }
-
-    /**
-     * Returns a new instance from a Token and an iterable of key-value parameters.
-     */
-    public static function fromToken(Stringable|string $value): self
-    {
-        return new self(Token::fromString($value));
-    }
-
-    /**
-     * Returns a new instance from a timestamp and an iterable of key-value parameters.
-     */
-    public static function fromTimestamp(int $timestamp): self
-    {
-        return new self((new DateTimeImmutable())->setTimestamp($timestamp));
-    }
-
-    /**
-     * Returns a new instance from a date format its date string representation and an iterable of key-value parameters.
-     *
-     * @throws SyntaxError if the format is invalid
-     */
-    public static function fromDateFormat(string $format, string $datetime): self
-    {
-        try {
-            $value = DateTimeImmutable::createFromFormat($format, $datetime);
-        } catch (Exception $exception) {
-            throw new SyntaxError('The date notation `'.$datetime.'` is incompatible with the date format `'.$format.'`.', 0, $exception);
-        }
-
-        return match (false) {
-            $value => throw new SyntaxError('The date notation `'.$datetime.'` is incompatible with the date format `'.$format.'`.'),
-            default => new self($value),
-        };
-    }
-
-    /**
-     * Returns a new instance from a string parsable by DateTimeImmutable constructor, an optional timezone and an iterable of key-value parameters.
-     *
-     * @throws SyntaxError if the format is invalid
-     */
-    public static function fromDateString(string $datetime, DateTimeZone|string|null $timezone = null): self
-    {
-        $timezone ??= date_default_timezone_get();
-        if (!$timezone instanceof DateTimeZone) {
-            try {
-                $timezone = new DateTimeZone($timezone);
-            } catch (Throwable $exception) {
-                throw new SyntaxError('The timezone could not be instantiated.', 0, $exception);
-            }
-        }
-
-        try {
-            $value = new DateTimeImmutable($datetime, $timezone);
-        } catch (Throwable $exception) {
-            throw new SyntaxError('Unable to create a '.DateTimeImmutable::class.' instance with the date notation `'.$datetime.'.`', 0, $exception);
-        }
-
-        return new self($value);
-    }
-
-    /**
-     * Returns a new instance from a DatetimeInterface implementing object.
-     *
-     * @throws SyntaxError if the format is invalid
-     */
-    public static function fromDate(DateTimeInterface $datetime): self
-    {
-        return new self($datetime);
-    }
-
-    public static function fromDecimal(int|float $value): self
-    {
-        return new self((float) $value);
-    }
-
-    public static function fromInteger(int|float $value): self
-    {
-        return new self((int) $value);
-    }
-
-    public static function fromString(Stringable|string $value): self
-    {
-        return new self((string) $value);
-    }
-
-    public static function true(): self
-    {
-        return new self(true);
-    }
-
-    public static function false(): self
-    {
-        return new self(false);
-    }
-
-    /**
-     * Serialize the Item value according to RFC8941.
-     *
-     * @see https://www.rfc-editor.org/rfc/rfc9651.html#section-4.1
-     */
-    public function serialize(?Ietf $rfc = Ietf::Rfc9651): string
-    {
-        $rfc ??= Ietf::Rfc9651;
-        if (!$rfc->supports($this->type)) {
-            throw MissingFeature::dueToLackOfSupport($this->type, $rfc);
-        }
-
-        return match (true) {
-            $this->value instanceof DateTimeImmutable => '@'.$this->value->getTimestamp(),
-            $this->value instanceof Token => $this->value->toString(),
-            $this->value instanceof Bytes => ':'.$this->value->encoded().':',
-            $this->value instanceof DisplayString => '%"'.$this->value->encoded().'"',
-            is_int($this->value) => (string) $this->value,
-            is_float($this->value) => (string) json_encode(round($this->value, 3, PHP_ROUND_HALF_EVEN), JSON_PRESERVE_ZERO_FRACTION),
-            $this->value,
-            false === $this->value => '?'.($this->value ? '1' : '0'),
-            default => '"'.preg_replace('/(["\\\])/', '\\\$1', $this->value).'"',
-        };
-    }
-
-    public function equals(mixed $value): bool
-    {
-        if ($value instanceof self) {
-            $value = $value->value;
-        }
-
-        return match (true) {
-            $this->value instanceof Bytes,
-            $this->value instanceof Token,
-            $this->value instanceof DisplayString => $this->value->equals($value),
-            $this->value instanceof DateTimeInterface && $value instanceof DateTimeInterface => $value == $this->value,
-            default => $value === $this->value,
-        };
-    }
-}
diff --git a/tests/DataTypeTest.php b/tests/DataTypeTest.php
index fe042df..34dc21e 100644
--- a/tests/DataTypeTest.php
+++ b/tests/DataTypeTest.php
@@ -98,7 +98,7 @@ public function it_will_fail_to_generate_rfc8941_structured_field_text_represena
     {
         $this->expectExceptionObject(MissingFeature::dueToLackOfSupport(Type::Date, Ietf::Rfc8941));
 
-        DataType::Dictionary->toRfc8941([['a', false], ['b', Item::fromDateString('+30 minutes')]]);
+        DataType::Dictionary->serialize([['a', false], ['b', Item::fromDateString('+30 minutes')]], Ietf::Rfc8941);
     }
 
     #[Test]
@@ -108,6 +108,6 @@ public function it_will_fail_to_parse_rfc9651_structured_field_text_represenatio
 
         $string = DataType::Dictionary->serialize([['a', false], ['b', Item::fromDateString('+30 minutes')]]);
 
-        DataType::Dictionary->fromRfc8941($string);
+        DataType::Dictionary->parse($string, Ietf::Rfc8941);
     }
 }
diff --git a/tests/DictionaryTest.php b/tests/DictionaryTest.php
index 9451321..9c806ec 100644
--- a/tests/DictionaryTest.php
+++ b/tests/DictionaryTest.php
@@ -6,6 +6,7 @@
 
 use LogicException;
 use PHPUnit\Framework\Attributes\Test;
+use TypeError;
 
 final class DictionaryTest extends StructuredFieldTestCase
 {
@@ -125,7 +126,7 @@ public function it_fails_to_add_an_item_with_wrong_key(): void
     #[Test]
     public function it_fails_to_insert_something_other_than_a_inner_list_or_an_item(): void
     {
-        $this->expectException(InvalidArgument::class);
+        $this->expectException(TypeError::class);
 
         Dictionary::new()->add('foo', Parameters::fromAssociative(['foo' => 'bar']));
     }
diff --git a/tests/OuterListTest.php b/tests/OuterListTest.php
index a7b522f..7386779 100644
--- a/tests/OuterListTest.php
+++ b/tests/OuterListTest.php
@@ -6,6 +6,7 @@
 
 use LogicException;
 use PHPUnit\Framework\Attributes\Test;
+use TypeError;
 
 final class OuterListTest extends StructuredFieldTestCase
 {
@@ -103,7 +104,7 @@ public function it_can_return_the_same_object_if_no_replace_is_needed(): void
     #[Test]
     public function it_fails_to_insert_something_other_than_a_inner_list_or_an_item(): void
     {
-        $this->expectException(InvalidArgument::class);
+        $this->expectException(TypeError::class);
 
         OuterList::new()->push(Dictionary::fromAssociative(['foo' => 'bar']));
     }
diff --git a/tests/ParserBench.php b/tests/ParserBench.php
index bdd85a6..a0fde92 100644
--- a/tests/ParserBench.php
+++ b/tests/ParserBench.php
@@ -12,7 +12,7 @@ final class ParserBench
 
     public function __construct()
     {
-        $this->parser = Parser::new();
+        $this->parser = new Parser(Ietf::Rfc9651);
     }
 
     #[Bench\Iterations(4)]
diff --git a/tests/ParserTest.php b/tests/ParserTest.php
index 1a9d6ca..f30f9e8 100644
--- a/tests/ParserTest.php
+++ b/tests/ParserTest.php
@@ -24,7 +24,8 @@ final class ParserTest extends StructuredFieldTestCase
     protected function setUp(): void
     {
         parent::setUp();
-        $this->parser = Parser::new();
+
+        $this->parser = new Parser(Ietf::Rfc9651);
     }
 
     #[Test]