diff --git a/.idea/php-test-framework.xml b/.idea/php-test-framework.xml
new file mode 100644
index 0000000..bf466ae
--- /dev/null
+++ b/.idea/php-test-framework.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="PhpTestFrameworkVersionCache">
+    <tools_cache>
+      <tool tool_name="PHPUnit">
+        <cache>
+          <versions>
+            <info id="Local/home/jclain/wop/php/nur-sery/vendor/autoload.php" version="9.6.13" />
+          </versions>
+        </cache>
+      </tool>
+    </tools_cache>
+  </component>
+</project>
\ No newline at end of file
diff --git a/src/schema/AssocSchema.php b/src/schema/AssocSchema.php
index af722f6..0c8704b 100644
--- a/src/schema/AssocSchema.php
+++ b/src/schema/AssocSchema.php
@@ -37,4 +37,8 @@ class AssocSchema extends Schema {
     if ($normalize) $definition = self::normalize($definition);
     $this->definition = $definition;
   }
+
+  function isAssoc(): bool {
+    return true;
+  }
 }
diff --git a/src/schema/ListSchema.php b/src/schema/ListSchema.php
index 0f9b6aa..879af16 100644
--- a/src/schema/ListSchema.php
+++ b/src/schema/ListSchema.php
@@ -37,4 +37,8 @@ class ListSchema extends Schema {
     if ($normalize) $definition = self::normalize($definition);
     $this->definition = $definition;
   }
+
+  function isList(): bool {
+    return true;
+  }
 }
diff --git a/src/schema/OldSchema.php b/src/schema/OldSchema.php
index 29e1b27..65e9dc9 100644
--- a/src/schema/OldSchema.php
+++ b/src/schema/OldSchema.php
@@ -21,60 +21,6 @@ use nulib\StateException;
 # format() et [formatter_func] --> formatter la valeur et retourner une chaine
 
 class OldSchema {
-  /**
-   * créer une nouvelle instance de cette classe à partir d'un schéma
-   *
-   * @param bool $normalized indique si le schéma est normalisé
-   * normalisé
-   */
-  static function new(&$md, $schema, bool $normalized=false): self {
-    if ($md === null) $md = new static($schema, !$normalized);
-    return $md;
-  }
-
-  static function normalize($schema): array {
-    if ($schema === null) throw new SchemaException("schema is required");
-    elseif (!is_array($schema)) $schema = [$schema];
-    #XXX
-    return $schema;
-  }
-
-  const SCHEMA = null;
-
-  function __construct($schema=null, bool $normalize=true) {
-    if ($schema === null) $schema = static::SCHEMA;
-    if ($normalize) $schema = self::normalize($schema);
-    $this->schema = $schema;
-  }
-
-  /**
-   * @var array schéma normalisé
-   *
-   * il y a 3 formes pour un schéma:
-   * - schéma valeur scalaire [0 => type, 1 => default, ...]
-   * - schéma tableau séquentiel [schema]
-   * - schéma tableau associatif [key => schema, ...]
-   */
-  protected $schema;
-
-  /**
-   * retourner true si le schéma est pour une valeur scalaire, false s'il s'agit
-   * du schéma d'un tableau (séquentiel ou associatif)
-   */
-  function isScalar(): bool {
-    return array_key_exists(0, $this->schema) && array_key_exists(1, $this->schema);
-  }
-
-  /** retourner true si le schéma est pour un tableau séquentiel */
-  function isSeq(): bool {
-    return array_key_exists(0, $this->schema) && !array_key_exists(1, $this->schema);
-  }
-
-  /** retourner true si le schéma est pour un tableau associatif */
-  function isAssoc(): bool {
-    return !array_key_exists(0, $this->schema) && !array_key_exists(1, $this->schema);
-  }
-
   /**
    * @var bool true si toutes les clés du schéma doivent exister, avec leur
    * valeur par défaut le cas échéant
diff --git a/src/schema/ScalarSchema.php b/src/schema/ScalarSchema.php
index 5a1f221..21dc011 100644
--- a/src/schema/ScalarSchema.php
+++ b/src/schema/ScalarSchema.php
@@ -1,9 +1,44 @@
 <?php
 namespace nur\sery\schema;
 
+use nulib\cl;
+use nur\sery\schema\ref\ref_schema;
+use nur\sery\schema\ref\ref_types;
+
+/**
+ * Class ScalarSchema
+ * 
+ * @property-read array $type
+ * @property-read mixed $default
+ * @property-read string|null $title
+ * @property-read bool $required
+ * @property-read bool $nullable
+ * @property-read string|array|null $desc
+ * @property-read callable|null $analyzerFunc
+ * @property-read callable|null $extractorFunc
+ * @property-read callable|null $parserFunc
+ * @property-read callable|null $normalizerFunc
+ * @property-read array|null $messages
+ * @property-read callable|null $formatterFunc
+ * @property-read mixed $format
+ * @property-read array $nature
+ * @property-read string|int|null $name
+ */
 class ScalarSchema extends Schema {
   /** @var array meta-schema d'un schéma de nature scalaire */
   const METASCHEMA = ref_schema::SCALAR_METASCHEMA;
+  const METASCHEMA_KEYS = [
+    "type", "default", "title", "required", "nullable", "desc",
+    "analyzer_func", "extractor_func", "parser_func", "normalizer_func", "messages",
+    "formatter_func", "format",
+    "", "name",
+  ];
+  const METASCHEMA_INDEXES = [
+    "type" => 0, "default" => 1, "title" => 2, "required" => 3, "nullable" => 4, "desc" => 5,
+    "analyzer_func" => 6, "extractor_func" => 7, "parser_func" => 8, "normalizer_func" => 9, "messages" => 10,
+    "formatter_func" => 11, "format" => 12,
+    "" => 13, "name" => 14,
+  ];
 
   /**
    * indiquer si $definition est une définition de schéma scalaire que
@@ -37,7 +72,82 @@ class ScalarSchema extends Schema {
   }
 
   static function normalize($definition): array {
-
+    if (!is_array($definition)) $definition = [$definition];
+    # s'assurer que toutes les clés existent avec leur valeur par défaut
+    $index = 0;
+    foreach (self::METASCHEMA_KEYS as $key) {
+      if (!array_key_exists($key, $definition)) {
+        if (array_key_exists($index, $definition)) {
+          $definition[$key] = $definition[$index];
+          unset($definition[$index]);
+          $index++;
+        } else {
+          $definition[$key] = self::METASCHEMA[$key][1];
+        }
+      }
+    }
+    # réordonner les clés numériques
+    if (cl::have_num_keys($definition)) {
+      $keys = array_keys($definition);
+      $index = 0;
+      foreach ($keys as $key) {
+        if (!is_int($key)) continue;
+        $definition[$index] = $definition[$key];
+        unset($definition[$key]);
+        $index++;
+      }
+    }
+    # type
+    $types = [];
+    $deftype = $definition["type"];
+    $nullable = $definition["nullable"];
+    if ($deftype === null) {
+      $types[] = null;
+      $nullable = true;
+    } else {
+      if (!is_array($deftype)) {
+        if (!is_string($deftype)) throw SchemaException::invalid_type($deftype);
+        $deftype = explode("|", $deftype);
+      }
+      foreach ($deftype as $type) {
+        if ($type === null || $type === "null") {
+          $nullable = true;
+          continue;
+        }
+        if (!is_string($type)) throw SchemaException::invalid_type($type);
+        if (substr($type, 0, 1) == "?") {
+          $type = substr($type, 1);
+          $nullable = true;
+        }
+        if ($type === "") throw SchemaException::invalid_type($type);
+        $type = cl::get(ref_types::ALIASES, $type, $type);
+        $types = array_merge($types, explode("|", $type));
+      }
+      if (!$types) throw SchemaException::invalid_schema("scalar: type is required");
+      $types = array_keys(array_fill_keys($types, true));
+    }
+    $definition["type"] = $types;
+    $definition["nullable"] = $nullable;
+    # nature
+    $nature = $definition[""];
+    self::ensure_array($nature);
+    if (!array_key_exists(0, $nature) || $nature[0] !== "scalar") {
+      throw SchemaException::invalid_schema("expected scalar nature");
+    }
+    $definition[""] = $nature;
+    # autres éléments
+    self::ensure_nstring($definition["title"]);
+    self::ensure_bool($definition["required"]);
+    self::ensure_bool($definition["nullable"]);
+    self::ensure_ncontent($definition["desc"]);
+    self::ensure_ncallable($definition["analyzer_func"]);
+    self::ensure_ncallable($definition["extractor_func"]);
+    self::ensure_ncallable($definition["parser_func"]);
+    self::ensure_ncallable($definition["normalizer_func"]);
+    self::ensure_narray($definition["messages"]);
+    self::ensure_ncallable($definition["formatter_func"]);
+    self::ensure_nkey($definition["name"]);
+    return $definition;
   }
 
   function __construct($definition=null, bool $normalize=true) {
@@ -45,4 +155,8 @@ class ScalarSchema extends Schema {
     if ($normalize) $definition = self::normalize($definition);
     $this->definition = $definition;
   }
+
+  function isScalar(): bool {
+    return true;
+  }
 }
diff --git a/src/schema/Schema.php b/src/schema/Schema.php
index 5519a1d..587c52f 100644
--- a/src/schema/Schema.php
+++ b/src/schema/Schema.php
@@ -1,6 +1,8 @@
 <?php
 namespace nur\sery\schema;
 
+use nulib\cl;
+
 abstract class Schema {
   /**
    * créer si besoin une nouvelle instance à partir d'une définition de schéma
@@ -20,6 +22,42 @@ abstract class Schema {
     return $md;
   }
 
+  protected static function ensure_nstring(&$string): void {
+    if ($string !== null && !is_string($string)) $string = strval($string);
+  }
+  protected static function ensure_string(&$string): void {
+    if (!is_string($string)) $string = strval($string);
+  }
+  protected static function ensure_nbool(&$bool): void {
+    if ($bool !== null && !is_bool($bool)) $bool = boolval($bool);
+  }
+  protected static function ensure_bool(&$bool): void {
+    if (!is_bool($bool)) $bool = boolval($bool);
+  }
+  protected static function ensure_ncallable(&$callable): void {
+    if ($callable !== null && !is_callable($callable)) {
+      throw SchemaException::invalid_callable($callable);
+    }
+  }
+  protected static function ensure_narray(&$array): void {
+    if ($array !== null && !is_array($array)) $array = cl::with($array);
+  }
+  protected static function ensure_array(&$array): void {
+    if (!is_array($array)) $array = cl::with($array);
+  }
+  protected static function ensure_nkey(&$key): void {
+    if ($key !== null && !is_string($key) && !is_int($key)) $key = strval($key);
+  }
+  protected static function ensure_key(&$key): void {
+    if (!is_string($key) && !is_int($key)) $key = strval($key);
+  }
+  protected static function ensure_ncontent(&$key): void {
+    if ($key !== null && !is_string($key) && !is_array($key)) $key = strval($key);
+  }
+  protected static function ensure_content(&$key): void {
+    if (!is_string($key) && !is_array($key)) $key = strval($key);
+  }
+
   /**
    * @var array définition du schéma, à redéfinir le cas échéant dans une classe
    * dérivée
@@ -28,4 +66,11 @@ abstract class Schema {
 
   /** @var array */
   protected $definition;
+
+  /** retourner true si le schéma est de nature tableau associatif */
+  function isAssoc(): bool { return false; }
+  /** retourner true si le schéma est de nature liste */
+  function isList(): bool { return false; }
+  /** retourner true si le schéma est de nature scalaire */
+  function isScalar(): bool { return false; }
 }
diff --git a/src/schema/SchemaException.php b/src/schema/SchemaException.php
index 2ff36ee..ac57759 100644
--- a/src/schema/SchemaException.php
+++ b/src/schema/SchemaException.php
@@ -4,7 +4,21 @@ namespace nur\sery\schema;
 use Exception;
 
 class SchemaException extends Exception {
-  static final function invalid_schema(): self {
-    return new static("invalid schema");
+  static final function invalid_schema(?string $message=null): self {
+    $invalid_schema = "invalid schema";
+    if ($message !== null) $invalid_schema .= ": $message";
+    return new static($invalid_schema);
+  }
+
+  static final function invalid_type($value, ?string $message=null): self {
+    $invalid_type = var_export($value, true).": invalid type";
+    if ($message !== null) $invalid_type .= ": $message";
+    return new static($invalid_type);
+  }
+
+  static final function invalid_callable($value, ?string $message=null): self {
+    $invalid_callable = var_export($value, true).": invalid callable";
+    if ($message !== null) $invalid_callable .= ": $message";
+    return new static($invalid_callable);
   }
 }
diff --git a/src/schema/ref_schema.php b/src/schema/ref/ref_schema.php
similarity index 69%
rename from src/schema/ref_schema.php
rename to src/schema/ref/ref_schema.php
index 7d5a734..5744276 100644
--- a/src/schema/ref_schema.php
+++ b/src/schema/ref/ref_schema.php
@@ -1,41 +1,9 @@
 <?php
-namespace nur\sery\schema;
+namespace nur\sery\schema\ref;
 
 class ref_schema {
-  const SCHEMA_SCHEMA = [
-    "type" => ["string", null, "" => 0,
-      "required" => true,
-      "desc" => "type de la valeur",
-    ],
-    "default" => [null, null, "" => 1,
-      "desc" => "valeur par défaut",
-    ],
-    "key" => ["?key", null, "" => "",
-      "desc" => "clé de la valeur si elle est dans un tableau",
-    ],
-    "required" => ["bool", false,
-      "desc" => "cette valeur est-elle requise?",
-    ],
-    "formatter" => ["?callable", null,
-      "desc" => "signature de la fonction: (value, format, type) => string",
-    ],
-    "parser" => ["?callable", null,
-      "desc" => "signature de la fonction: (value, type) => [value, result]",
-    ],
-    "messages" => ["?array", null,
-      "desc" => "message à afficher en cas d'erreur d'analyse",
-    ],
-  ];
-
-  const MESSAGES = [
-    "absent" => "{key}: Vous devez spécifier cette valeur",
-    "null" => "{key}: Cette valeur ne doit pas être nulle",
-    "empty" => "{key}: Cette valeur ne doit pas être vide",
-    "invalid" => "{key}: {orig}: cette valeur est invalide",
-  ];
-
   /** @var array schéma des natures de schéma */
-  public const NATURE_METASCHEMA = [
+  const NATURE_METASCHEMA = [
     "nature" => ["string", null, "nature du schéma",
       "key" => 0,
       "allowed_values" => ["assoc", "list", "scalar"],
@@ -49,7 +17,7 @@ class ref_schema {
   ];
 
   /** @var array meta-schema d'un schéma de nature scalaire */
-  public const SCALAR_METASCHEMA = [
+  const SCALAR_METASCHEMA = [
     "type" => ["array", null, "types possibles de la valeur", "required" => true],
     "default" => [null, null, "valeur par défaut si la valeur n'existe pas"],
     "title" => ["?string", null, "libellé de la valeur"],
@@ -63,7 +31,16 @@ class ref_schema {
     "messages" => ["?array", null, "messages à afficher en cas d'erreur d'analyse"],
     "formatter_func" => ["?callable", null, "fonction qui formatte la valeur pour affichage"],
     "format" => [null, null, "format à utiliser pour l'affichage"],
-    "" => ["" => ["assoc", "schema" => self::NATURE_METASCHEMA]],
+    "" => ["array", "scalar", "nature du schéma",
+      "" => ["assoc", "schema" => self::NATURE_METASCHEMA],
+    ],
     "name" => ["?key", null, "identifiant de la valeur"],
   ];
+
+  const MESSAGES = [
+    "absent" => "{key}: Vous devez spécifier cette valeur",
+    "null" => "{key}: Cette valeur ne doit pas être nulle",
+    "empty" => "{key}: Cette valeur ne doit pas être vide",
+    "invalid" => "{key}: {orig}: cette valeur est invalide",
+  ];
 }
diff --git a/src/schema/ref/ref_types.php b/src/schema/ref/ref_types.php
new file mode 100644
index 0000000..a3733b5
--- /dev/null
+++ b/src/schema/ref/ref_types.php
@@ -0,0 +1,9 @@
+<?php
+namespace nur\sery\schema\ref;
+
+class ref_types {
+  const ALIASES = [
+    "key" => "string|int",
+    "content" => "string|array",
+  ];
+}
diff --git a/tests/schema/ScalarSchemaTest.php b/tests/schema/ScalarSchemaTest.php
new file mode 100644
index 0000000..40cdd2a
--- /dev/null
+++ b/tests/schema/ScalarSchemaTest.php
@@ -0,0 +1,60 @@
+<?php
+namespace nur\sery\schema;
+
+use nulib\tests\TestCase;
+
+class ScalarSchemaTest extends TestCase {
+  const NULL_SCHEMA = [
+    "type" => [null],
+    "default" => null,
+    "title" => null,
+    "required" => false,
+    "nullable" => true,
+    "desc" => null,
+    "analyzer_func" => null,
+    "extractor_func" => null,
+    "parser_func" => null,
+    "normalizer_func" => null,
+    "messages" => null,
+    "formatter_func" => null,
+    "format" => null,
+    "" => ["scalar"],
+    "name" => null,
+  ];
+
+  static function schema(array $schema): array {
+    return array_merge(self::NULL_SCHEMA, $schema);
+  }
+
+  function testNormalize() {
+    self::assertSame(self::NULL_SCHEMA, ScalarSchema::normalize(null));
+    self::assertSame(self::NULL_SCHEMA, ScalarSchema::normalize([]));
+    self::assertSame(self::NULL_SCHEMA, ScalarSchema::normalize([null]));
+    self::assertException(SchemaException::class, function () {
+      ScalarSchema::normalize([[]]);
+    });
+    self::assertException(SchemaException::class, function () {
+      ScalarSchema::normalize([[null]]);
+    });
+
+    $string = self::schema(["type" => ["string"], "nullable" => false]);
+    self::assertSame($string, ScalarSchema::normalize("string"));
+    self::assertSame($string, ScalarSchema::normalize(["string"]));
+
+    $nstring = self::schema(["type" => ["string"]]);
+    self::assertSame($nstring, ScalarSchema::normalize(["?string"]));
+    self::assertSame($nstring, ScalarSchema::normalize(["?string|null"]));
+    self::assertSame($nstring, ScalarSchema::normalize(["string|null"]));
+    self::assertSame($nstring, ScalarSchema::normalize([["?string", "null"]]));
+    self::assertSame($nstring, ScalarSchema::normalize([["string", "null"]]));
+    self::assertSame($nstring, ScalarSchema::normalize([["string", null]]));
+
+    $key = self::schema(["type" => ["string", "int"], "nullable" => false]);
+    self::assertSame($key, ScalarSchema::normalize("key"));
+    self::assertSame($key, ScalarSchema::normalize("key|string"));
+
+    $nkey = self::schema(["type" => ["string", "int"], "nullable" => true]);
+    self::assertSame($nkey, ScalarSchema::normalize("?key"));
+    self::assertSame($nkey, ScalarSchema::normalize("?key|string"));
+  }
+}