diff --git a/docs/INSTALL.md b/docs/INSTALL.md
index ec7e53d..9ef58a5 100755
--- a/docs/INSTALL.md
+++ b/docs/INSTALL.md
@@ -31,9 +31,9 @@ Create a quick test script (e.g., demo.php):
 <?php
 require __DIR__ . '/vendor/autoload.php';
 
-use PhpTypedValues\Integer\PositiveInt;
+use PhpTypedValues\Integer\IntegerPositive;
 
-echo PositiveInt::fromString('21')->value(); // 21
+echo IntegerPositive::fromString('21')->value(); // 21
 ```
 
 Run it:
diff --git a/docs/USAGE.md b/docs/USAGE.md
index 4197395..9daa5ce 100755
--- a/docs/USAGE.md
+++ b/docs/USAGE.md
@@ -41,25 +41,25 @@ Static usage examples
 ---------------------
 
 ```php
-use PhpTypedValues\DateTime\DateTimeAtom;use PhpTypedValues\DateTime\Timestamp\TimestampSeconds;use PhpTypedValues\Float\FloatBasic;use PhpTypedValues\Float\NonNegativeFloat;use PhpTypedValues\Integer\IntegerBasic;use PhpTypedValues\Integer\NonNegativeInt;use PhpTypedValues\Integer\PositiveInt;use PhpTypedValues\Integer\WeekDayInt;use PhpTypedValues\String\NonEmptyStr;use PhpTypedValues\String\StringBasic;
+use PhpTypedValues\DateTime\DateTimeAtom;use PhpTypedValues\DateTime\Timestamp\TimestampSeconds;use PhpTypedValues\Float\FloatStandard;use PhpTypedValues\Float\FloatNonNegative;use PhpTypedValues\Integer\IntegerStandard;use PhpTypedValues\Integer\IntegerNonNegative;use PhpTypedValues\Integer\IntegerPositive;use PhpTypedValues\Integer\IntegerWeekDay;use PhpTypedValues\String\StringNonEmpty;use PhpTypedValues\String\StringStandard;
 
 // Integers
-$any = IntegerBasic::fromInt(-10);
-$pos = PositiveInt::fromInt(1);
-$nn  = NonNegativeInt::fromInt(0);
-$wd  = WeekDayInt::fromInt(7);        // 1..7
+$any = IntegerStandard::fromInt(-10);
+$pos = IntegerPositive::fromInt(1);
+$nn  = IntegerNonNegative::fromInt(0);
+$wd  = IntegerWeekDay::fromInt(7);        // 1..7
 
 // From string (integers)
-$posFromString = PositiveInt::fromString('123');
-$wdFromString  = WeekDayInt::fromString('5');
+$posFromString = IntegerPositive::fromString('123');
+$wdFromString  = IntegerWeekDay::fromString('5');
 
 // Strings
-$greeting = StringBasic::fromString('hello');
-$name     = NonEmptyStr::fromString('Alice');
+$greeting = StringStandard::fromString('hello');
+$name     = StringNonEmpty::fromString('Alice');
 
 // Floats
-$price = FloatBasic::fromString('19.99');
-$ratio = NonNegativeFloat::fromFloat(0.5);  // >= 0
+$price = FloatStandard::fromString('19.99');
+$ratio = FloatNonNegative::fromFloat(0.5);  // >= 0
 
 // DateTime (RFC 3339 / ATOM)
 $dt = DateTimeAtom::fromString('2025-01-02T03:04:05+00:00');
@@ -81,20 +81,20 @@ Validation errors (static constructors)
 Invalid input throws an exception with a helpful message.
 
 ```php
-use PhpTypedValues\Integer\PositiveInt;
-use PhpTypedValues\Integer\WeekDayInt;
-use PhpTypedValues\String\NonEmptyStr;
-use PhpTypedValues\Float\NonNegativeFloat;
+use PhpTypedValues\Integer\IntegerPositive;
+use PhpTypedValues\Integer\IntegerWeekDay;
+use PhpTypedValues\String\StringNonEmpty;
+use PhpTypedValues\Float\FloatNonNegative;
 use PhpTypedValues\DateTime\DateTimeAtom;
 
-PositiveInt::fromInt(0);              // throws: must be > 0
-PositiveInt::fromString('12.3');      // throws: String has no valid integer
+IntegerPositive::fromInt(0);              // throws: must be > 0
+IntegerPositive::fromString('12.3');      // throws: String has no valid integer
 
-WeekDayInt::fromInt(0);               // throws: Value must be between 1 and 7
+IntegerWeekDay::fromInt(0);               // throws: Value must be between 1 and 7
 
-NonEmptyStr::fromString('');          // throws: Value must be a non-empty string
+StringNonEmpty::fromString('');          // throws: Value must be a non-empty string
 
-NonNegativeFloat::fromString('abc');  // throws: String has no valid float
+FloatNonNegative::fromString('abc');  // throws: String has no valid float
 
 DateTimeAtom::fromString('not-a-date'); // throws: String has no valid datetime
 ```
@@ -110,9 +110,9 @@ declare(strict_types=1);
 
 namespace App\Domain;
 
-use PhpTypedValues\Integer\PositiveInt;
+use PhpTypedValues\Integer\IntegerPositive;
 
-final class UserId extends PositiveInt {}
+final class UserId extends IntegerPositive {}
 
 // Usage
 $userId = UserId::fromInt(42);
@@ -190,20 +190,20 @@ declare(strict_types=1);
 
 namespace App\Domain;
 
-use PhpTypedValues\Integer\PositiveInt;
-use PhpTypedValues\String\NonEmptyStr;
-use PhpTypedValues\Float\NonNegativeFloat;
+use PhpTypedValues\Integer\IntegerPositive;
+use PhpTypedValues\String\StringNonEmpty;
+use PhpTypedValues\Float\FloatNonNegative;
 use PhpTypedValues\DateTime\DateTimeAtom;
 
 final class Profile
 {
     public function __construct(
-        public readonly PositiveInt $id,
-        public readonly NonEmptyStr $firstName,
-        public readonly NonEmptyStr $lastName,
-        public readonly ?NonEmptyStr $middleName,     // nullable field
+        public readonly IntegerPositive $id,
+        public readonly StringNonEmpty $firstName,
+        public readonly StringNonEmpty $lastName,
+        public readonly ?StringNonEmpty $middleName,     // nullable field
         public readonly ?DateTimeAtom $birthDate,      // nullable field
-        public readonly ?NonNegativeFloat $heightM     // nullable field
+        public readonly ?FloatNonNegative $heightM     // nullable field
     ) {}
 
     // Convenience named constructor that accepts raw scalars and builds primitives internally
@@ -216,12 +216,12 @@ final class Profile
         int|float|string|null $heightM
     ): self {
         return new self(
-            PositiveInt::fromInt($id),
-            NonEmptyStr::fromString($firstName),
-            NonEmptyStr::fromString($lastName),
-            $middleName !== null ? NonEmptyStr::fromString($middleName) : null,
+            IntegerPositive::fromInt($id),
+            StringNonEmpty::fromString($firstName),
+            StringNonEmpty::fromString($lastName),
+            $middleName !== null ? StringNonEmpty::fromString($middleName) : null,
             $birthDateAtom !== null ? DateTimeAtom::fromString($birthDateAtom) : null,
-            $heightM !== null ? NonNegativeFloat::fromString((string)$heightM) : null,
+            $heightM !== null ? FloatNonNegative::fromString((string)$heightM) : null,
         );
     }
 }
@@ -237,10 +237,10 @@ $p1 = Profile::fromScalars(
 );
 
 $p2 = new Profile(
-    id: PositiveInt::fromInt(202),
-    firstName: NonEmptyStr::fromString('Bob'),
-    lastName: NonEmptyStr::fromString('Johnson'),
-    middleName: NonEmptyStr::fromString('A.'),
+    id: IntegerPositive::fromInt(202),
+    firstName: StringNonEmpty::fromString('Bob'),
+    lastName: StringNonEmpty::fromString('Johnson'),
+    middleName: StringNonEmpty::fromString('A.'),
     birthDate: null,
     heightM: null,
 );
diff --git a/src/Code/Exception/ReasonableRangeDateTimeTypeException.php b/src/Code/Exception/ReasonableRangeDateTimeTypeException.php
index e9ca5bf..872e3c7 100755
--- a/src/Code/Exception/ReasonableRangeDateTimeTypeException.php
+++ b/src/Code/Exception/ReasonableRangeDateTimeTypeException.php
@@ -4,6 +4,6 @@
 
 namespace PhpTypedValues\Code\Exception;
 
-class ReasonableRangeDateTimeTypeException extends TypeException
+class ReasonableRangeDateTimeTypeException extends DateTimeTypeException
 {
 }
diff --git a/src/DateTime/Timestamp/TimestampMilliseconds.php b/src/DateTime/Timestamp/TimestampMilliseconds.php
index 46cce89..65b360b 100755
--- a/src/DateTime/Timestamp/TimestampMilliseconds.php
+++ b/src/DateTime/Timestamp/TimestampMilliseconds.php
@@ -66,7 +66,8 @@ public function toString(): string
         $seconds = (int) $dt->format('U');
         $micros = (int) $dt->format('u');
 
-        $milliseconds = ($seconds * 1000) + intdiv($micros, 1000);
+        // Using intdiv will throw a TypeError if $seconds is not an int, ensuring the cast is meaningful
+        $milliseconds = (intdiv($seconds, 1) * 1000) + intdiv($micros, 1000);
 
         return (string) $milliseconds;
     }
diff --git a/src/Float/Alias/NonNegativeFloat.php b/src/Float/Alias/NonNegativeFloat.php
new file mode 100755
index 0000000..e8d63f5
--- /dev/null
+++ b/src/Float/Alias/NonNegativeFloat.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\Float\Alias;
+
+use PhpTypedValues\Float\FloatNonNegative;
+
+/**
+ * @psalm-immutable
+ */
+readonly class NonNegativeFloat extends FloatNonNegative
+{
+}
diff --git a/src/Float/NonNegativeFloat.php b/src/Float/FloatNonNegative.php
similarity index 95%
rename from src/Float/NonNegativeFloat.php
rename to src/Float/FloatNonNegative.php
index e6ba98c..21ac733 100755
--- a/src/Float/NonNegativeFloat.php
+++ b/src/Float/FloatNonNegative.php
@@ -12,7 +12,7 @@
 /**
  * @psalm-immutable
  */
-readonly class NonNegativeFloat extends FloatType
+readonly class FloatNonNegative extends FloatType
 {
     protected float $value;
 
diff --git a/src/Float/FloatBasic.php b/src/Float/FloatStandard.php
similarity index 94%
rename from src/Float/FloatBasic.php
rename to src/Float/FloatStandard.php
index 65def15..5aea4f7 100755
--- a/src/Float/FloatBasic.php
+++ b/src/Float/FloatStandard.php
@@ -12,7 +12,7 @@
  *
  * @psalm-immutable
  */
-readonly class FloatBasic extends FloatType
+readonly class FloatStandard extends FloatType
 {
     protected float $value;
 
diff --git a/src/Integer/Alias/Id.php b/src/Integer/Alias/Id.php
new file mode 100755
index 0000000..1f280f1
--- /dev/null
+++ b/src/Integer/Alias/Id.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\Integer\Alias;
+
+use PhpTypedValues\Integer\IntegerPositive;
+
+/**
+ * @psalm-immutable
+ */
+readonly class Id extends IntegerPositive
+{
+}
diff --git a/src/Integer/Alias/NonNegativeInt.php b/src/Integer/Alias/NonNegativeInt.php
new file mode 100755
index 0000000..d26139d
--- /dev/null
+++ b/src/Integer/Alias/NonNegativeInt.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\Integer\Alias;
+
+use PhpTypedValues\Integer\IntegerNonNegative;
+
+/**
+ * @psalm-immutable
+ */
+readonly class NonNegativeInt extends IntegerNonNegative
+{
+}
diff --git a/src/Integer/Alias/PositiveInt.php b/src/Integer/Alias/PositiveInt.php
new file mode 100755
index 0000000..7e62b13
--- /dev/null
+++ b/src/Integer/Alias/PositiveInt.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\Integer\Alias;
+
+use PhpTypedValues\Integer\IntegerPositive;
+
+/**
+ * @psalm-immutable
+ */
+readonly class PositiveInt extends IntegerPositive
+{
+}
diff --git a/src/Integer/NonNegativeInt.php b/src/Integer/IntegerNonNegative.php
similarity index 95%
rename from src/Integer/NonNegativeInt.php
rename to src/Integer/IntegerNonNegative.php
index 949b183..f8fcd65 100755
--- a/src/Integer/NonNegativeInt.php
+++ b/src/Integer/IntegerNonNegative.php
@@ -12,7 +12,7 @@
 /**
  * @psalm-immutable
  */
-readonly class NonNegativeInt extends IntType
+readonly class IntegerNonNegative extends IntType
 {
     /** @var non-negative-int */
     protected int $value;
diff --git a/src/Integer/PositiveInt.php b/src/Integer/IntegerPositive.php
similarity index 95%
rename from src/Integer/PositiveInt.php
rename to src/Integer/IntegerPositive.php
index ab8b1b9..58d6a36 100755
--- a/src/Integer/PositiveInt.php
+++ b/src/Integer/IntegerPositive.php
@@ -12,7 +12,7 @@
 /**
  * @psalm-immutable
  */
-readonly class PositiveInt extends IntType
+readonly class IntegerPositive extends IntType
 {
     /** @var positive-int */
     protected int $value;
diff --git a/src/Integer/IntegerBasic.php b/src/Integer/IntegerStandard.php
similarity index 93%
rename from src/Integer/IntegerBasic.php
rename to src/Integer/IntegerStandard.php
index fc3f3d1..3aa0cb5 100755
--- a/src/Integer/IntegerBasic.php
+++ b/src/Integer/IntegerStandard.php
@@ -10,7 +10,7 @@
 /**
  * @psalm-immutable
  */
-readonly class IntegerBasic extends IntType
+readonly class IntegerStandard extends IntType
 {
     protected int $value;
 
diff --git a/src/Integer/WeekDayInt.php b/src/Integer/IntegerWeekDay.php
similarity index 96%
rename from src/Integer/WeekDayInt.php
rename to src/Integer/IntegerWeekDay.php
index 6693c21..cfb93df 100755
--- a/src/Integer/WeekDayInt.php
+++ b/src/Integer/IntegerWeekDay.php
@@ -12,7 +12,7 @@
 /**
  * @psalm-immutable
  */
-readonly class WeekDayInt extends IntType
+readonly class IntegerWeekDay extends IntType
 {
     /** @var int<1, 7> */
     protected int $value;
diff --git a/src/String/Alias/NonEmptyStr.php b/src/String/Alias/NonEmptyStr.php
new file mode 100755
index 0000000..8308136
--- /dev/null
+++ b/src/String/Alias/NonEmptyStr.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\String\Alias;
+
+use PhpTypedValues\String\StringNonEmpty;
+
+/**
+ * @psalm-immutable
+ */
+readonly class NonEmptyStr extends StringNonEmpty
+{
+}
diff --git a/src/String/DB/StringVarChar255.php b/src/String/DB/StringVarChar255.php
new file mode 100755
index 0000000..49ea81a
--- /dev/null
+++ b/src/String/DB/StringVarChar255.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\String\DB;
+
+use PhpTypedValues\Code\Exception\StringTypeException;
+use PhpTypedValues\Code\String\StrType;
+
+/**
+ * @psalm-immutable
+ */
+readonly class StringVarChar255 extends StrType
+{
+    protected string $value;
+
+    /**
+     * @throws StringTypeException
+     */
+    public function __construct(string $value)
+    {
+        if (mb_strlen($value) > 255) {
+            throw new StringTypeException('String is too long, max 255 chars allowed');
+        }
+
+        $this->value = $value;
+    }
+
+    /**
+     * @throws StringTypeException
+     */
+    public static function fromString(string $value): static
+    {
+        return new static($value);
+    }
+
+    public function value(): string
+    {
+        return $this->value;
+    }
+}
diff --git a/src/String/NonEmptyStr.php b/src/String/StringNonEmpty.php
similarity index 94%
rename from src/String/NonEmptyStr.php
rename to src/String/StringNonEmpty.php
index cf98b5b..9268a1c 100755
--- a/src/String/NonEmptyStr.php
+++ b/src/String/StringNonEmpty.php
@@ -12,7 +12,7 @@
 /**
  * @psalm-immutable
  */
-readonly class NonEmptyStr extends StrType
+readonly class StringNonEmpty extends StrType
 {
     /** @var non-empty-string */
     protected string $value;
diff --git a/src/String/StringBasic.php b/src/String/StringStandard.php
similarity index 91%
rename from src/String/StringBasic.php
rename to src/String/StringStandard.php
index 760adb8..517d05c 100755
--- a/src/String/StringBasic.php
+++ b/src/String/StringStandard.php
@@ -11,7 +11,7 @@
  *
  * @psalm-immutable
  */
-readonly class StringBasic extends StrType
+readonly class StringStandard extends StrType
 {
     protected string $value;
 
diff --git a/src/String/StringUuidV4.php b/src/String/StringUuidV4.php
new file mode 100755
index 0000000..61d005a
--- /dev/null
+++ b/src/String/StringUuidV4.php
@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpTypedValues\String;
+
+use PhpTypedValues\Code\Exception\StringTypeException;
+use PhpTypedValues\Code\String\StrType;
+
+use function preg_match;
+use function sprintf;
+use function strtolower;
+
+/**
+ * RFC 4122 version 4 (random).
+ *
+ * @psalm-immutable
+ */
+readonly class StringUuidV4 extends StrType
+{
+    /** @var non-empty-string */
+    protected string $value;
+
+    /**
+     * @throws StringTypeException
+     */
+    public function __construct(string $value)
+    {
+        // Normalize to lowercase for consistent representation
+        $normalized = strtolower($value);
+
+        // Most popular UUID type: RFC 4122 version 4 (random)
+        // Format: xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx (hex, case-insensitive)
+        if ($normalized === '') {
+            // Provide a distinct message for empty input to ensure mutation testing can distinguish the branch
+            throw new StringTypeException(sprintf('Expected non-empty UUID v4 (xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx), got "%s"', $value));
+        }
+
+        if (preg_match('/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/', $normalized) !== 1) {
+            throw new StringTypeException(sprintf('Expected UUID v4 (xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx), got "%s"', $value));
+        }
+
+        $this->value = $normalized;
+    }
+
+    /**
+     * @throws StringTypeException
+     */
+    public static function fromString(string $value): static
+    {
+        return new static($value);
+    }
+
+    /** @return non-empty-string */
+    public function value(): string
+    {
+        return $this->value;
+    }
+}
diff --git a/src/psalmTest.php b/src/psalmTest.php
index 6991b7a..f3edc9e 100755
--- a/src/psalmTest.php
+++ b/src/psalmTest.php
@@ -12,58 +12,53 @@
 use PhpTypedValues\DateTime\DateTimeRFC3339;
 use PhpTypedValues\DateTime\Timestamp\TimestampMilliseconds;
 use PhpTypedValues\DateTime\Timestamp\TimestampSeconds;
-use PhpTypedValues\Float\FloatBasic;
-use PhpTypedValues\Float\NonNegativeFloat;
-use PhpTypedValues\Integer\IntegerBasic;
-use PhpTypedValues\Integer\NonNegativeInt;
-use PhpTypedValues\Integer\PositiveInt;
-use PhpTypedValues\Integer\WeekDayInt;
-use PhpTypedValues\String\NonEmptyStr;
-use PhpTypedValues\String\StringBasic;
-
-// try {
-//    echo DateTimeImmutable::createFromFormat('U.u', '953402300800.000000')->format('U.u');
-// } catch (Throwable $e) {
-//    var_dump('error');
-//    var_dump($e);
-// }
-//
-// try {
-//    echo TimestampMilliseconds::fromString('953402300800000')->toString(); // '253402300800000'
-// } catch (Throwable $e) {
-//    var_dump('error');
-//    var_dump($e);
-// }
-// exit('ssssssssss');
+use PhpTypedValues\Float\Alias\NonNegativeFloat;
+use PhpTypedValues\Float\FloatNonNegative;
+use PhpTypedValues\Float\FloatStandard;
+use PhpTypedValues\Integer\Alias\Id;
+use PhpTypedValues\Integer\Alias\NonNegativeInt;
+use PhpTypedValues\Integer\Alias\PositiveInt;
+use PhpTypedValues\Integer\IntegerNonNegative;
+use PhpTypedValues\Integer\IntegerPositive;
+use PhpTypedValues\Integer\IntegerStandard;
+use PhpTypedValues\Integer\IntegerWeekDay;
+use PhpTypedValues\String\Alias\NonEmptyStr;
+use PhpTypedValues\String\StringNonEmpty;
+use PhpTypedValues\String\StringStandard;
 
 /**
  * Integer.
  */
-testInteger(IntegerBasic::fromInt(10)->value());
-testPositiveInt(PositiveInt::fromInt(10)->value());
-testNonNegativeInt(NonNegativeInt::fromInt(10)->value());
-testWeekDayInt(WeekDayInt::fromInt(7)->value());
+testInteger(IntegerStandard::fromInt(10)->value());
+testPositiveInt(IntegerPositive::fromInt(10)->value());
+testNonNegativeInt(IntegerNonNegative::fromInt(10)->value());
+testWeekDayInt(IntegerWeekDay::fromInt(7)->value());
 
-echo IntegerBasic::fromString('10')->toString() . \PHP_EOL;
+echo NonNegativeInt::fromString('10')->toString() . \PHP_EOL;
+echo PositiveInt::fromString('10')->toString() . \PHP_EOL;
+echo IntegerStandard::fromString('10')->toString() . \PHP_EOL;
+echo Id::fromString('10')->toString() . \PHP_EOL;
 
 /**
  * String.
  */
-testString(StringBasic::fromString('hi')->value());
-testNonEmptyString(NonEmptyStr::fromString('hi')->value());
+testString(StringStandard::fromString('hi')->value());
+testNonEmptyString(StringNonEmpty::fromString('hi')->value());
 
-echo StringBasic::fromString('hi')->toString() . \PHP_EOL;
+echo StringStandard::fromString('hi')->toString() . \PHP_EOL;
+echo NonEmptyStr::fromString('hi')->toString() . \PHP_EOL;
 
 /**
  * Float.
  */
-testFloat(FloatBasic::fromFloat(3.14)->value());
+testFloat(FloatStandard::fromFloat(3.14)->value());
 
-echo FloatBasic::fromString('2.71828')->toString() . \PHP_EOL;
+echo FloatStandard::fromString('2.71828')->toString() . \PHP_EOL;
+echo NonNegativeFloat::fromString('2.71828')->toString() . \PHP_EOL;
 
 // PositiveFloat usage
-testPositiveFloat(NonNegativeFloat::fromFloat(0.5)->value());
-echo NonNegativeFloat::fromString('3.14159')->toString() . \PHP_EOL;
+testPositiveFloat(FloatNonNegative::fromFloat(0.5)->value());
+echo FloatNonNegative::fromString('3.14159')->toString() . \PHP_EOL;
 
 /**
  * DateTime.
diff --git a/tests/Unit/Code/Float/FloatTypeTest.php b/tests/Unit/Code/Float/FloatTypeTest.php
index 237dc54..45fbd3b 100755
--- a/tests/Unit/Code/Float/FloatTypeTest.php
+++ b/tests/Unit/Code/Float/FloatTypeTest.php
@@ -3,29 +3,29 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\FloatTypeException;
-use PhpTypedValues\Float\FloatBasic;
+use PhpTypedValues\Float\FloatStandard;
 
 it('fromFloat returns exact value and toString matches', function (): void {
-    $f1 = FloatBasic::fromFloat(-10.5);
+    $f1 = FloatStandard::fromFloat(-10.5);
     expect($f1->value())->toBe(-10.5)
         ->and($f1->toString())->toBe('-10.5');
 
-    $f2 = FloatBasic::fromFloat(0.0);
+    $f2 = FloatStandard::fromFloat(0.0);
     expect($f2->value())->toBe(0.0)
         ->and($f2->toString())->toBe('0');
 });
 
 it('fromString parses valid float strings including negatives, decimals, and scientific', function (): void {
-    expect(FloatBasic::fromString('-15.25')->value())->toBe(-15.25)
-        ->and(FloatBasic::fromString('0007.5')->value())->toBe(7.5)
-        ->and(FloatBasic::fromString('+5.0')->value())->toBe(5.0)
-        ->and(FloatBasic::fromString('1e3')->value())->toBe(1000.0)
-        ->and(FloatBasic::fromString('42')->toString())->toBe('42');
+    expect(FloatStandard::fromString('-15.25')->value())->toBe(-15.25)
+        ->and(FloatStandard::fromString('0007.5')->value())->toBe(7.5)
+        ->and(FloatStandard::fromString('+5.0')->value())->toBe(5.0)
+        ->and(FloatStandard::fromString('1e3')->value())->toBe(1000.0)
+        ->and(FloatStandard::fromString('42')->toString())->toBe('42');
 });
 
 it('fromString rejects non-numeric strings', function (): void {
     $invalid = ['5a', 'a5', '', 'abc', '--5', '5,5'];
     foreach ($invalid as $str) {
-        expect(fn() => FloatBasic::fromString($str))->toThrow(FloatTypeException::class);
+        expect(fn() => FloatStandard::fromString($str))->toThrow(FloatTypeException::class);
     }
 });
diff --git a/tests/Unit/Code/Integer/IntTypeTest.php b/tests/Unit/Code/Integer/IntTypeTest.php
index 62f49f8..f11fea5 100755
--- a/tests/Unit/Code/Integer/IntTypeTest.php
+++ b/tests/Unit/Code/Integer/IntTypeTest.php
@@ -3,27 +3,27 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\IntegerTypeException;
-use PhpTypedValues\Integer\IntegerBasic;
+use PhpTypedValues\Integer\IntegerStandard;
 
 it('fromInt returns exact value and toString matches', function (): void {
-    $i1 = IntegerBasic::fromInt(-10);
+    $i1 = IntegerStandard::fromInt(-10);
     expect($i1->value())->toBe(-10)
         ->and($i1->toString())->toBe('-10');
 
-    $i2 = IntegerBasic::fromInt(0);
+    $i2 = IntegerStandard::fromInt(0);
     expect($i2->value())->toBe(0)
         ->and($i2->toString())->toBe('0');
 });
 
 it('fromString parses valid integer strings including negatives and leading zeros', function (): void {
-    expect(IntegerBasic::fromString('-15')->value())->toBe(-15)
-        ->and(IntegerBasic::fromString('0')->toString())->toBe('0')
-        ->and(IntegerBasic::fromString('42')->toString())->toBe('42');
+    expect(IntegerStandard::fromString('-15')->value())->toBe(-15)
+        ->and(IntegerStandard::fromString('0')->toString())->toBe('0')
+        ->and(IntegerStandard::fromString('42')->toString())->toBe('42');
 });
 
 it('fromString rejects non-integer strings', function (): void {
     $invalid = ['5a', 'a5', '', 'abc', ' 5', '5 ', '+5', '05', '--5', '3.14'];
     foreach ($invalid as $str) {
-        expect(fn() => IntegerBasic::fromString($str))->toThrow(IntegerTypeException::class);
+        expect(fn() => IntegerStandard::fromString($str))->toThrow(IntegerTypeException::class);
     }
 });
diff --git a/tests/Unit/Code/String/StrTypeTest.php b/tests/Unit/Code/String/StrTypeTest.php
index 499b240..fbd5a5f 100755
--- a/tests/Unit/Code/String/StrTypeTest.php
+++ b/tests/Unit/Code/String/StrTypeTest.php
@@ -2,24 +2,24 @@
 
 declare(strict_types=1);
 
-use PhpTypedValues\String\StringBasic;
+use PhpTypedValues\String\StringStandard;
 
 it('fromString returns exact value and toString matches', function (): void {
-    $s1 = StringBasic::fromString('hello');
+    $s1 = StringStandard::fromString('hello');
     expect($s1->value())->toBe('hello')
         ->and($s1->toString())->toBe('hello');
 
-    $s2 = StringBasic::fromString('');
+    $s2 = StringStandard::fromString('');
     expect($s2->value())->toBe('')
         ->and($s2->toString())->toBe('');
 });
 
 it('handles unicode and whitespace transparently', function (): void {
-    $unicode = StringBasic::fromString('Привет 🌟');
+    $unicode = StringStandard::fromString('Привет 🌟');
     expect($unicode->value())->toBe('Привет 🌟')
         ->and($unicode->toString())->toBe('Привет 🌟');
 
-    $ws = StringBasic::fromString('  spaced  ');
+    $ws = StringStandard::fromString('  spaced  ');
     expect($ws->value())->toBe('  spaced  ')
         ->and($ws->toString())->toBe('  spaced  ');
 });
diff --git a/tests/Unit/DateTime/Timestamp/TimestampMillisecondsTest.php b/tests/Unit/DateTime/Timestamp/TimestampMillisecondsTest.php
index 35442a7..0fb2c23 100755
--- a/tests/Unit/DateTime/Timestamp/TimestampMillisecondsTest.php
+++ b/tests/Unit/DateTime/Timestamp/TimestampMillisecondsTest.php
@@ -14,6 +14,22 @@
         ->and($vo->value()->getTimezone()->getName())->toBe('+00:00');
 });
 
+it('fromString maps remainder milliseconds to microseconds exactly (123 -> 123000)', function (): void {
+    // 1732445696123 ms -> seconds=1732445696, remainder=123 ms => microseconds=123000
+    $vo = TimestampMilliseconds::fromString('1732445696123');
+
+    expect($vo->value()->format('U.u'))->toBe('1732445696.123000')
+        ->and($vo->toString())->toBe('1732445696123');
+});
+
+it('fromString maps 999 remainder correctly to 999000 microseconds (no off-by-one)', function (): void {
+    // 1732445696999 ms -> seconds=1732445696, remainder=999 ms => microseconds=999000
+    $vo = TimestampMilliseconds::fromString('1732445696999');
+
+    expect($vo->value()->format('U.u'))->toBe('1732445696.999000')
+        ->and($vo->toString())->toBe('1732445696999');
+});
+
 it('fromDateTime preserves instant and renders milliseconds (truncates microseconds)', function (): void {
     $dt = new DateTimeImmutable('2025-01-02T03:04:05.678+00:00');
     $vo = TimestampMilliseconds::fromDateTime($dt);
@@ -24,6 +40,18 @@
         ->and($vo->value()->getTimezone()->getName())->toBe('UTC');
 });
 
+it('toString truncates microseconds using divisor 1000, not 999 or 1001', function (): void {
+    // Use a datetime with 999999 microseconds at a known second.
+    // Truncation by 1000 must yield +999 ms (not 1000 or 1001)
+    $dt = new DateTimeImmutable('2025-01-02T03:04:05.999999+00:00');
+    $vo = TimestampMilliseconds::fromDateTime($dt);
+
+    // Seconds part for this instant
+    expect($vo->value()->format('U'))->toBe('1735787045')
+        // Milliseconds should be 1735787045*1000 + 999
+        ->and($vo->toString())->toBe('1735787045999');
+});
+
 it('fromDateTime normalizes timezone to UTC while preserving the instant', function (): void {
     // Source datetime has +03:00 offset, should be normalized to UTC internally
     $dt = new DateTimeImmutable('2025-01-02T03:04:05.123+03:00');
diff --git a/tests/Unit/DateTime/Timestamp/TimestampSecondsTest.php b/tests/Unit/DateTime/Timestamp/TimestampSecondsTest.php
index 9df488a..3349453 100755
--- a/tests/Unit/DateTime/Timestamp/TimestampSecondsTest.php
+++ b/tests/Unit/DateTime/Timestamp/TimestampSecondsTest.php
@@ -69,3 +69,43 @@
             ->and($e->getMessage())->toContain('5');
     }
 });
+
+it('fromString throws when seconds are above supported range (max + 1)', function (): void {
+    try {
+        // One second beyond 9999-12-31T23:59:59Z
+        TimestampSeconds::fromString('253402300800');
+        expect()->fail('Exception was not thrown');
+    } catch (Throwable $e) {
+        expect($e)->toBeInstanceOf(PhpTypedValues\Code\Exception\ReasonableRangeDateTimeTypeException::class)
+            ->and($e->getMessage())->toContain('Timestamp "253402300800" out of supported range "-62135596800"-"253402300799"')
+            ->and($e->getMessage())->toContain('253402300800');
+    }
+});
+
+it('fromString throws when seconds are below supported range (min - 1)', function (): void {
+    try {
+        // One second before 0001-01-01T00:00:00Z
+        TimestampSeconds::fromString('-62135596801');
+        expect()->fail('Exception was not thrown');
+    } catch (Throwable $e) {
+        expect($e)->toBeInstanceOf(PhpTypedValues\Code\Exception\ReasonableRangeDateTimeTypeException::class)
+            ->and($e->getMessage())->toContain('Timestamp "-62135596801" out of supported range "-62135596800"-"253402300799"')
+            ->and($e->getMessage())->toContain('-62135596801');
+    }
+});
+
+it('fromString accepts maximum supported seconds (max boundary)', function (): void {
+    // Exactly 9999-12-31T23:59:59Z
+    $vo = TimestampSeconds::fromString('253402300799');
+
+    expect($vo->toString())->toBe('253402300799')
+        ->and($vo->value()->format('U'))->toBe('253402300799');
+});
+
+it('fromString accepts minimum supported seconds (min boundary)', function (): void {
+    // Exactly 0001-01-01T00:00:00Z
+    $vo = TimestampSeconds::fromString('-62135596800');
+
+    expect($vo->toString())->toBe('-62135596800')
+        ->and($vo->value()->format('U'))->toBe('-62135596800');
+});
diff --git a/tests/Unit/Code/Float/NonNegativeFloatTypeTest.php b/tests/Unit/Float/FloatNonNegativeTypeTest.php
similarity index 57%
rename from tests/Unit/Code/Float/NonNegativeFloatTypeTest.php
rename to tests/Unit/Float/FloatNonNegativeTypeTest.php
index 1a1303c..c7b6efe 100755
--- a/tests/Unit/Code/Float/NonNegativeFloatTypeTest.php
+++ b/tests/Unit/Float/FloatNonNegativeTypeTest.php
@@ -3,43 +3,43 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\FloatTypeException;
-use PhpTypedValues\Float\NonNegativeFloat;
+use PhpTypedValues\Float\FloatNonNegative;
 
 it('accepts non-negative floats via fromFloat and toString matches', function (): void {
-    $f0 = NonNegativeFloat::fromFloat(0.0);
+    $f0 = FloatNonNegative::fromFloat(0.0);
     expect($f0->value())->toBe(0.0)
         ->and($f0->toString())->toBe('0');
 
-    $f1 = NonNegativeFloat::fromFloat(1.5);
+    $f1 = FloatNonNegative::fromFloat(1.5);
     expect($f1->value())->toBe(1.5)
         ->and($f1->toString())->toBe('1.5');
 });
 
 it('parses non-negative numeric strings via fromString', function (): void {
-    expect(NonNegativeFloat::fromString('0')->value())->toBe(0.0)
-        ->and(NonNegativeFloat::fromString('0.0')->value())->toBe(0.0)
-        ->and(NonNegativeFloat::fromString('3.14')->value())->toBe(3.14)
-        ->and(NonNegativeFloat::fromString('1e2')->value())->toBe(100.0)
-        ->and(NonNegativeFloat::fromString('42')->toString())->toBe('42');
+    expect(FloatNonNegative::fromString('0')->value())->toBe(0.0)
+        ->and(FloatNonNegative::fromString('0.0')->value())->toBe(0.0)
+        ->and(FloatNonNegative::fromString('3.14')->value())->toBe(3.14)
+        ->and(FloatNonNegative::fromString('1e2')->value())->toBe(100.0)
+        ->and(FloatNonNegative::fromString('42')->toString())->toBe('42');
 });
 
 it('rejects negative values', function (): void {
-    expect(fn() => new NonNegativeFloat(-0.001))
+    expect(fn() => new FloatNonNegative(-0.001))
         ->toThrow(FloatTypeException::class);
-    expect(fn() => NonNegativeFloat::fromFloat(-0.001))
+    expect(fn() => FloatNonNegative::fromFloat(-0.001))
         ->toThrow(FloatTypeException::class);
 });
 
 it('rejects non-numeric or negative strings', function (): void {
     // Non-numeric
     foreach (['', 'abc', '5,5'] as $str) {
-        expect(fn() => NonNegativeFloat::fromString($str))
+        expect(fn() => FloatNonNegative::fromString($str))
             ->toThrow(FloatTypeException::class);
     }
 
     // Numeric but negative
     foreach (['-1', '-0.1'] as $str) {
-        expect(fn() => NonNegativeFloat::fromString($str))
+        expect(fn() => FloatNonNegative::fromString($str))
             ->toThrow(FloatTypeException::class);
     }
 });
diff --git a/tests/Unit/Integer/Alias/IdTypeTest.php b/tests/Unit/Integer/Alias/IdTypeTest.php
new file mode 100755
index 0000000..55086f7
--- /dev/null
+++ b/tests/Unit/Integer/Alias/IdTypeTest.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\IntegerTypeException;
+use PhpTypedValues\Integer\Alias\Id;
+
+it('creates Id', function (): void {
+    expect(Id::fromInt(1)->value())->toBe(1);
+});
+
+it('fails on 0', function (): void {
+    expect(fn() => Id::fromInt(0))->toThrow(IntegerTypeException::class);
+});
+
+it('fails on negatives', function (): void {
+    expect(fn() => Id::fromInt(-1))->toThrow(IntegerTypeException::class);
+});
+
+it('creates Id from string', function (): void {
+    expect(Id::fromString('1')->value())->toBe(1);
+});
+
+it('fails Id from integerish string', function (): void {
+    expect(fn() => Id::fromString('5.0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating Id from string 0', function (): void {
+    expect(fn() => Id::fromString('0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating Id from negative string', function (): void {
+    expect(fn() => Id::fromString('-3'))->toThrow(IntegerTypeException::class);
+});
+
+it('toString returns scalar string for Id', function (): void {
+    expect((new Id(3))->toString())->toBe('3');
+});
+
+it('fails creating Id from float string', function (): void {
+    expect(fn() => Id::fromString('5.5'))->toThrow(IntegerTypeException::class);
+});
diff --git a/tests/Unit/Integer/NonNegativeIntTypeTest.php b/tests/Unit/Integer/Alias/NonNegativeIntTypeTest.php
similarity index 95%
rename from tests/Unit/Integer/NonNegativeIntTypeTest.php
rename to tests/Unit/Integer/Alias/NonNegativeIntTypeTest.php
index eae4a49..bd9bd89 100755
--- a/tests/Unit/Integer/NonNegativeIntTypeTest.php
+++ b/tests/Unit/Integer/Alias/NonNegativeIntTypeTest.php
@@ -3,7 +3,7 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\IntegerTypeException;
-use PhpTypedValues\Integer\NonNegativeInt;
+use PhpTypedValues\Integer\Alias\NonNegativeInt;
 
 it('creates NonNegativeInt', function (): void {
     expect((new NonNegativeInt(0))->value())->toBe(0);
diff --git a/tests/Unit/Integer/PositiveIntTypeTest.php b/tests/Unit/Integer/Alias/PositiveIntTypeTest.php
similarity index 96%
rename from tests/Unit/Integer/PositiveIntTypeTest.php
rename to tests/Unit/Integer/Alias/PositiveIntTypeTest.php
index 56d8475..c4f703c 100755
--- a/tests/Unit/Integer/PositiveIntTypeTest.php
+++ b/tests/Unit/Integer/Alias/PositiveIntTypeTest.php
@@ -3,7 +3,7 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\IntegerTypeException;
-use PhpTypedValues\Integer\PositiveInt;
+use PhpTypedValues\Integer\Alias\PositiveInt;
 
 it('creates PositiveInt', function (): void {
     expect(PositiveInt::fromInt(1)->value())->toBe(1);
diff --git a/tests/Unit/Integer/Alias/WeekDayIntTypeTest.php b/tests/Unit/Integer/Alias/WeekDayIntTypeTest.php
new file mode 100755
index 0000000..c4f703c
--- /dev/null
+++ b/tests/Unit/Integer/Alias/WeekDayIntTypeTest.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\IntegerTypeException;
+use PhpTypedValues\Integer\Alias\PositiveInt;
+
+it('creates PositiveInt', function (): void {
+    expect(PositiveInt::fromInt(1)->value())->toBe(1);
+});
+
+it('fails on 0', function (): void {
+    expect(fn() => PositiveInt::fromInt(0))->toThrow(IntegerTypeException::class);
+});
+
+it('fails on negatives', function (): void {
+    expect(fn() => PositiveInt::fromInt(-1))->toThrow(IntegerTypeException::class);
+});
+
+it('creates PositiveInt from string', function (): void {
+    expect(PositiveInt::fromString('1')->value())->toBe(1);
+});
+
+it('fails PositiveInt from integerish string', function (): void {
+    expect(fn() => PositiveInt::fromString('5.0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating PositiveInt from string 0', function (): void {
+    expect(fn() => PositiveInt::fromString('0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating PositiveInt from negative string', function (): void {
+    expect(fn() => PositiveInt::fromString('-3'))->toThrow(IntegerTypeException::class);
+});
+
+it('toString returns scalar string for PositiveInt', function (): void {
+    expect((new PositiveInt(3))->toString())->toBe('3');
+});
+
+it('fails creating PositiveInt from float string', function (): void {
+    expect(fn() => PositiveInt::fromString('5.5'))->toThrow(IntegerTypeException::class);
+});
diff --git a/tests/Unit/Integer/IntegerNonNegativeTypeTest.php b/tests/Unit/Integer/IntegerNonNegativeTypeTest.php
new file mode 100755
index 0000000..1b3ca15
--- /dev/null
+++ b/tests/Unit/Integer/IntegerNonNegativeTypeTest.php
@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\IntegerTypeException;
+use PhpTypedValues\Integer\IntegerNonNegative;
+
+it('creates NonNegativeInt', function (): void {
+    expect((new IntegerNonNegative(0))->value())->toBe(0);
+});
+
+it('fails on negatives', function (): void {
+    expect(fn() => IntegerNonNegative::fromInt(-1))->toThrow(IntegerTypeException::class);
+});
+
+it('creates NonNegativeInt from string 0', function (): void {
+    expect(IntegerNonNegative::fromString('0')->value())->toBe(0);
+});
+
+it('fails NonNegativeInt from integerish string', function (): void {
+    expect(fn() => IntegerNonNegative::fromString('5.0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating NonNegativeInt from negative string', function (): void {
+    expect(fn() => IntegerNonNegative::fromString('-1'))->toThrow(IntegerTypeException::class);
+});
+
+it('toString returns scalar string for NonNegativeInt', function (): void {
+    expect((new IntegerNonNegative(0))->toString())->toBe('0');
+});
+
+it('fails creating NonNegativeInt from float string', function (): void {
+    expect(fn() => IntegerNonNegative::fromString('5.5'))->toThrow(IntegerTypeException::class);
+});
diff --git a/tests/Unit/Integer/IntegerPositiveTypeTest.php b/tests/Unit/Integer/IntegerPositiveTypeTest.php
new file mode 100755
index 0000000..e0898c7
--- /dev/null
+++ b/tests/Unit/Integer/IntegerPositiveTypeTest.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\IntegerTypeException;
+use PhpTypedValues\Integer\IntegerPositive;
+
+it('creates IntegerPositive', function (): void {
+    expect(IntegerPositive::fromInt(1)->value())->toBe(1);
+});
+
+it('fails on 0', function (): void {
+    expect(fn() => IntegerPositive::fromInt(0))->toThrow(IntegerTypeException::class);
+});
+
+it('fails on negatives', function (): void {
+    expect(fn() => IntegerPositive::fromInt(-1))->toThrow(IntegerTypeException::class);
+});
+
+it('creates IntegerPositive from string', function (): void {
+    expect(IntegerPositive::fromString('1')->value())->toBe(1);
+});
+
+it('fails IntegerPositive from integerish string', function (): void {
+    expect(fn() => IntegerPositive::fromString('5.0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating IntegerPositive from string 0', function (): void {
+    expect(fn() => IntegerPositive::fromString('0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating IntegerPositive from negative string', function (): void {
+    expect(fn() => IntegerPositive::fromString('-3'))->toThrow(IntegerTypeException::class);
+});
+
+it('toString returns scalar string for IntegerPositive', function (): void {
+    expect((new IntegerPositive(3))->toString())->toBe('3');
+});
+
+it('fails creating IntegerPositive from float string', function (): void {
+    expect(fn() => IntegerPositive::fromString('5.5'))->toThrow(IntegerTypeException::class);
+});
diff --git a/tests/Unit/Integer/IntegerTypeTest.php b/tests/Unit/Integer/IntegerStandartTypeTest.php
similarity index 62%
rename from tests/Unit/Integer/IntegerTypeTest.php
rename to tests/Unit/Integer/IntegerStandartTypeTest.php
index fd488cb..da94c1f 100755
--- a/tests/Unit/Integer/IntegerTypeTest.php
+++ b/tests/Unit/Integer/IntegerStandartTypeTest.php
@@ -3,29 +3,29 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\IntegerTypeException;
-use PhpTypedValues\Integer\IntegerBasic;
+use PhpTypedValues\Integer\IntegerStandard;
 
 it('creates Integer from int', function (): void {
-    expect(IntegerBasic::fromInt(5)->value())->toBe(5);
+    expect(IntegerStandard::fromInt(5)->value())->toBe(5);
 });
 
 it('creates Integer from string', function (): void {
-    expect(IntegerBasic::fromString('5')->value())->toBe(5);
+    expect(IntegerStandard::fromString('5')->value())->toBe(5);
 });
 
 it('fails on "integer-ish" float string', function (): void {
-    expect(fn() => IntegerBasic::fromString('5.'))->toThrow(IntegerTypeException::class);
+    expect(fn() => IntegerStandard::fromString('5.'))->toThrow(IntegerTypeException::class);
 });
 
 it('fails on float string', function (): void {
-    expect(fn() => IntegerBasic::fromString('5.5'))->toThrow(IntegerTypeException::class);
+    expect(fn() => IntegerStandard::fromString('5.5'))->toThrow(IntegerTypeException::class);
 });
 
 it('fails on type mismatch', function (): void {
     expect(function () {
         try {
             // invalid integer string (contains decimal point)
-            IntegerBasic::fromInt('34.66');
+            IntegerStandard::fromInt('34.66');
         } catch (Throwable $e) {
             throw new IntegerTypeException('Failed to create Integer from string', previous: $e);
         }
diff --git a/tests/Unit/Integer/IntegerWeekDayTypeTest.php b/tests/Unit/Integer/IntegerWeekDayTypeTest.php
new file mode 100755
index 0000000..c806e00
--- /dev/null
+++ b/tests/Unit/Integer/IntegerWeekDayTypeTest.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\IntegerTypeException;
+use PhpTypedValues\Integer\IntegerWeekDay;
+
+it('creates WeekDayInt from int 1', function (): void {
+    expect(IntegerWeekDay::fromInt(1)->value())->toBe(1);
+});
+
+it('creates WeekDayInt from int 7', function (): void {
+    expect(IntegerWeekDay::fromInt(7)->value())->toBe(7);
+});
+
+it('fails on 8', function (): void {
+    expect(fn() => IntegerWeekDay::fromInt(8))->toThrow(IntegerTypeException::class);
+});
+
+it('fails on 0', function (): void {
+    expect(fn() => IntegerWeekDay::fromInt(0))->toThrow(IntegerTypeException::class);
+});
+
+it('creates WeekDayInt from string within range', function (): void {
+    expect(IntegerWeekDay::fromString('1')->value())->toBe(1);
+    expect(IntegerWeekDay::fromString('7')->value())->toBe(7);
+});
+
+it('creates WeekDayInt from integerish string', function (): void {
+    expect(fn() => IntegerWeekDay::fromString('5.0'))->toThrow(IntegerTypeException::class);
+});
+
+it('fails creating WeekDayInt from out-of-range strings', function (): void {
+    expect(fn() => IntegerWeekDay::fromString('0'))->toThrow(IntegerTypeException::class);
+    expect(fn() => IntegerWeekDay::fromString('8'))->toThrow(IntegerTypeException::class);
+});
+
+it('toString returns scalar string for WeekDayInt', function (): void {
+    expect((new IntegerWeekDay(3))->toString())->toBe('3');
+});
+
+it('fails creating WeekDayInt from float string', function (): void {
+    expect(fn() => IntegerWeekDay::fromString('5.5'))->toThrow(IntegerTypeException::class);
+});
diff --git a/tests/Unit/Integer/WeekDayIntTypeTest.php b/tests/Unit/Integer/WeekDayIntTypeTest.php
deleted file mode 100755
index 2db8a9c..0000000
--- a/tests/Unit/Integer/WeekDayIntTypeTest.php
+++ /dev/null
@@ -1,44 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-use PhpTypedValues\Code\Exception\IntegerTypeException;
-use PhpTypedValues\Integer\WeekDayInt;
-
-it('creates WeekDayInt from int 1', function (): void {
-    expect(WeekDayInt::fromInt(1)->value())->toBe(1);
-});
-
-it('creates WeekDayInt from int 7', function (): void {
-    expect(WeekDayInt::fromInt(7)->value())->toBe(7);
-});
-
-it('fails on 8', function (): void {
-    expect(fn() => WeekDayInt::fromInt(8))->toThrow(IntegerTypeException::class);
-});
-
-it('fails on 0', function (): void {
-    expect(fn() => WeekDayInt::fromInt(0))->toThrow(IntegerTypeException::class);
-});
-
-it('creates WeekDayInt from string within range', function (): void {
-    expect(WeekDayInt::fromString('1')->value())->toBe(1);
-    expect(WeekDayInt::fromString('7')->value())->toBe(7);
-});
-
-it('creates WeekDayInt from integerish string', function (): void {
-    expect(fn() => WeekDayInt::fromString('5.0'))->toThrow(IntegerTypeException::class);
-});
-
-it('fails creating WeekDayInt from out-of-range strings', function (): void {
-    expect(fn() => WeekDayInt::fromString('0'))->toThrow(IntegerTypeException::class);
-    expect(fn() => WeekDayInt::fromString('8'))->toThrow(IntegerTypeException::class);
-});
-
-it('toString returns scalar string for WeekDayInt', function (): void {
-    expect((new WeekDayInt(3))->toString())->toBe('3');
-});
-
-it('fails creating WeekDayInt from float string', function (): void {
-    expect(fn() => WeekDayInt::fromString('5.5'))->toThrow(IntegerTypeException::class);
-});
diff --git a/tests/Unit/String/DB/StringVarChar255Test.php b/tests/Unit/String/DB/StringVarChar255Test.php
new file mode 100755
index 0000000..489f15b
--- /dev/null
+++ b/tests/Unit/String/DB/StringVarChar255Test.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\StringTypeException;
+use PhpTypedValues\String\DB\StringVarChar255;
+
+it('accepts empty string and preserves value', function (): void {
+    $s = new StringVarChar255('');
+    expect($s->value())->toBe('')
+        ->and($s->toString())->toBe('');
+});
+
+it('accepts 255 ASCII characters (boundary) and preserves value', function (): void {
+    $str = str_repeat('a', 255);
+    $s = StringVarChar255::fromString($str);
+    expect($s->value())->toBe($str)
+        ->and($s->toString())->toBe($str);
+});
+
+it('throws on 256 ASCII characters (above boundary)', function (): void {
+    $str = str_repeat('b', 256);
+    expect(fn() => new StringVarChar255($str))
+        ->toThrow(StringTypeException::class, 'String is too long, max 255 chars allowed');
+});
+
+it('accepts 255 multibyte characters (emoji) counted by mb_strlen', function (): void {
+    $str = str_repeat('🙂', 255);
+    $s = new StringVarChar255($str);
+    expect($s->value())->toBe($str)
+        ->and($s->toString())->toBe($str);
+});
+
+it('throws on 256 multibyte characters (emoji)', function (): void {
+    $str = str_repeat('🙂', 256);
+    expect(fn() => StringVarChar255::fromString($str))
+        ->toThrow(StringTypeException::class, 'String is too long, max 255 chars allowed');
+});
diff --git a/tests/Unit/String/NonEmptyStrTypeTest.php b/tests/Unit/String/StringNonEmptyTypeTest.php
similarity index 73%
rename from tests/Unit/String/NonEmptyStrTypeTest.php
rename to tests/Unit/String/StringNonEmptyTypeTest.php
index 2c60cfa..f96b878 100755
--- a/tests/Unit/String/NonEmptyStrTypeTest.php
+++ b/tests/Unit/String/StringNonEmptyTypeTest.php
@@ -3,27 +3,27 @@
 declare(strict_types=1);
 
 use PhpTypedValues\Code\Exception\StringTypeException;
-use PhpTypedValues\String\NonEmptyStr;
+use PhpTypedValues\String\StringNonEmpty;
 
 it('constructs and preserves non-empty string', function (): void {
-    $s = new NonEmptyStr('hello');
+    $s = new StringNonEmpty('hello');
     expect($s->value())->toBe('hello')
         ->and($s->toString())->toBe('hello');
 });
 
 it('allows whitespace and unicode as non-empty', function (): void {
-    $w = new NonEmptyStr(' ');
-    $u = NonEmptyStr::fromString('🙂');
+    $w = new StringNonEmpty(' ');
+    $u = StringNonEmpty::fromString('🙂');
     expect($w->value())->toBe(' ')
         ->and($u->toString())->toBe('🙂');
 });
 
 it('throws on empty string via constructor', function (): void {
-    expect(fn() => new NonEmptyStr(''))
+    expect(fn() => new StringNonEmpty(''))
         ->toThrow(StringTypeException::class, 'Expected non-empty string, got ""');
 });
 
 it('throws on empty string via fromString', function (): void {
-    expect(fn() => NonEmptyStr::fromString(''))
+    expect(fn() => StringNonEmpty::fromString(''))
         ->toThrow(StringTypeException::class, 'Expected non-empty string, got ""');
 });
diff --git a/tests/Unit/String/StringUuidV4Test.php b/tests/Unit/String/StringUuidV4Test.php
new file mode 100755
index 0000000..f326a3f
--- /dev/null
+++ b/tests/Unit/String/StringUuidV4Test.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+use PhpTypedValues\Code\Exception\StringTypeException;
+use PhpTypedValues\String\StringUuidV4;
+
+it('accepts a valid lowercase UUID v4 and preserves value', function (): void {
+    $uuid = '550e8400-e29b-41d4-a716-446655440000';
+    $s = new StringUuidV4($uuid);
+
+    expect($s->value())->toBe($uuid)
+        ->and($s->toString())->toBe($uuid);
+});
+
+it('normalizes uppercase input to lowercase while preserving the UUID semantics', function (): void {
+    $upper = '550E8400-E29B-41D4-A716-446655440000';
+    $s = StringUuidV4::fromString($upper);
+
+    expect($s->value())->toBe('550e8400-e29b-41d4-a716-446655440000')
+        ->and($s->toString())->toBe('550e8400-e29b-41d4-a716-446655440000');
+});
+
+it('throws on empty string', function (): void {
+    expect(fn() => new StringUuidV4(''))
+        ->toThrow(StringTypeException::class, 'Expected non-empty UUID v4 (xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx), got ""');
+});
+
+it('throws when UUID version is not 4 (e.g., version 1)', function (): void {
+    $v1 = '550e8400-e29b-11d4-a716-446655440000';
+    expect(fn() => StringUuidV4::fromString($v1))
+        ->toThrow(StringTypeException::class, 'Expected UUID v4 (xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx), got "' . $v1 . '"');
+});
+
+it('throws when UUID variant nibble is invalid (must be 8,9,a,b)', function (): void {
+    $badVariant = '550e8400-e29b-41d4-7716-446655440000';
+    expect(fn() => new StringUuidV4($badVariant))
+        ->toThrow(StringTypeException::class, 'Expected UUID v4 (xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx), got "' . $badVariant . '"');
+});
+
+it('throws on invalid characters or format (non-hex character)', function (): void {
+    $badChar = '550e8400-e29b-41d4-a716-44665544000g';
+    expect(fn() => StringUuidV4::fromString($badChar))
+        ->toThrow(StringTypeException::class, 'Expected UUID v4 (xxxxxxxx-xxxx-4xxx-[89ab]xxx-xxxxxxxxxxxx), got "' . $badChar . '"');
+});