diff --git a/src/app/cli/ArgDef.php b/src/app/cli/ArgDef.php
index 8674e56..c783290 100644
--- a/src/app/cli/ArgDef.php
+++ b/src/app/cli/ArgDef.php
@@ -11,29 +11,29 @@ class ArgDef {
   const ARGS_NONE = 0, ARGS_MANDATORY = 1, ARGS_OPTIONAL = 2;
   const ACTION_SET = 0, ACTION_INC = 1, ACTION_DEC = 2, ACTION_FUNC = 3;
 
-  function __construct(array $def) {
+  protected static function parse_def(ArgDef $dest, array $def): void {
     [$options, $params] = cl::split_assoc($def);
 
     $args = $params["args"] ?? null;
     $args ??= $params["arg"] ?? null;
     if ($args === true) $args = 1;
     if (is_int($args)) $args = array_fill(0, $args, "value");
-    $this->args = cl::withn($args);
+    $dest->args ??= cl::withn($args);
 
-    $this->argsdesc = $params["argsdesc"] ?? null;
+    $dest->argsdesc ??= $params["argsdesc"] ?? null;
 
-    $extends = $params["extends"] ?? null;
-    if ($extends !== null) {
-      A::merge($extends["add"], $options);
-      $this->extends = $extends;
+    $parent = $params["parent"] ?? null;
+    if ($parent !== null) {
+      A::merge($parent["add"], $options);
+      A::merge($dest->parents, [$parent]);
     } else {
-      $this->addOptions($options);
+      $dest->addOptions($options);
     }
 
-    $this->ensureArray = $params["ensure_array"] ?? null;
+    $dest->ensureArray ??= $params["ensure_array"] ?? null;
     $action = $params["action"] ?? null;
-    $func = null;
     if ($action !== null) {
+      $func = null;
       switch ($action) {
       case "--set":
         $action = self::ACTION_SET;
@@ -49,16 +49,32 @@ class ArgDef {
         $action = self::ACTION_FUNC;
         break;
       }
+      $dest->action ??= $action;
+      $dest->func ??= $func;
     }
-    $this->action = $action;
-    $this->func = $func;
-    $this->inverse = $params["inverse"] ?? false;
-    $this->value = $params["value"] ?? null;
-    $this->name = $params["name"] ?? null;
-    $this->property = $params["property"] ?? null;
-    $this->key = $params["key"] ?? null;
+    $dest->inverse ??= $params["inverse"] ?? false;
+    $dest->value ??= $params["value"] ?? null;
+    $dest->name ??= $params["name"] ?? null;
+    $dest->property ??= $params["property"] ?? null;
+    $dest->key ??= $params["key"] ?? null;
 
-    $this->help = $params["help"] ?? null;
+    $dest->help ??= $params["help"] ?? null;
+  }
+
+  protected static function merge_parse_def(ArgDef $dest, array $def): void {
+    $defaults = $defs["defaults"] ?? null;
+    if ($defaults !== null) self::merge_parse_def($dest, $defaults);
+
+    self::parse_def($dest, $def);
+
+    $merges = $defs["merges"] ?? null;
+    $merge = $defs["merge"] ?? null;
+    if ($merge !== null) $merges[] = $merge;
+    if ($merges !== null) self::merge_parse_def($dest, $merges);
+  }
+
+  function __construct(array $def) {
+    self::merge_parse_def($this, $def);
   }
 
   protected ?array $options = [];
@@ -67,6 +83,7 @@ class ArgDef {
     return array_keys($this->options);
   }
 
+  public bool $isHelp = false;
   public bool $isRemains = false;
   public bool $haveShortOptions = false;
   public bool $haveLongOptions = false;
@@ -159,18 +176,20 @@ class ArgDef {
     unset($this->options[$option]);
   }
 
-  protected ?array $extends = null;
+  protected ?array $parents = null;
 
-  /** traiter le paramètre extends */
-  function processExtends(): void {
-    $extends = $this->extends;
-    if ($extends === null) return;
-    $base = $extends["arg"] ?? null;
-    if ($base === null) return;
-    $base = new self($base);
-    $this->options = $base->options;
-    $this->removeOptions(varray::withn($extends["remove"] ?? null));
-    $this->addOptions(varray::withn($extends["add"] ?? null));
+  /** traiter le paramètre parent */
+  function processParents(?ArgDefs $argDefs=null): void {
+    $parents = $this->parents;
+    if ($parents === null) return;
+    foreach ($parents as $parent) {
+      $argDef = $parent["arg"] ?? null;
+      if ($argDef === null) continue;
+      $argDef = new self($argDef);
+      $this->options = $argDef->options;
+      $this->removeOptions(varray::withn($parent["remove"] ?? null));
+      $this->addOptions(varray::withn($parent["add"] ?? null));
+    }
   }
 
   /** mettre à jour le type d'option */
@@ -178,6 +197,7 @@ class ArgDef {
     $haveShortOptions = false;
     $haveLongOptions = false;
     $haveCommands = false;
+    $isHelp = false;
     $isRemains = true;
     foreach ($this->options as $option) {
       $isRemains = false;
@@ -192,11 +212,13 @@ class ArgDef {
         $haveCommands = true;
         break;
       }
+      if ($option["option"] === "--help") $isHelp = true;
     }
-    $this->isRemains = $isRemains;
     $this->haveShortOptions = $haveShortOptions;
     $this->haveLongOptions = $haveLongOptions;
     $this->haveCommands = $haveCommands;
+    $this->isHelp = $isHelp;
+    $this->isRemains = $isRemains;
   }
 
   protected ?array $args = null;
@@ -207,8 +229,8 @@ class ArgDef {
    */
   function processArgs(): void {
     $args = $this->args;
+    $haveArgs = boolval($args);
     if ($args === null) {
-      $haveArgs = false;
       $optionalArgs = null;
       foreach ($this->options as $option) {
         switch ($option["args_type"]) {
diff --git a/src/app/cli/ArgDefs.php b/src/app/cli/ArgDefs.php
index 0c19bf8..118689c 100644
--- a/src/app/cli/ArgDefs.php
+++ b/src/app/cli/ArgDefs.php
@@ -2,47 +2,67 @@
 namespace nulib\app\cli;
 
 use nulib\cl;
+use nulib\php\types\vbool;
 
-class ArgDefs {
-  function __construct(array $defs) {
+abstract class ArgDefs {
+  protected static function parse_defs(SimpleArgDefs $dest, array $defs, ?array &$argDefs): void {
     [$defs, $params] = cl::split_assoc($defs);
 
-    $argDefs = [];
+    # méta-informations
+    $dest->prefix ??= $params["prefix"] ?? null;
+    $dest->name ??= $params["name"] ?? null;
+    $dest->purpose ??= $params["purpose"] ?? null;
+    $dest->usage ??= $params["usage"] ?? null;
+    $dest->description ??= $params["description"] ?? null;
+    $dest->suffix ??= $params["suffix"] ?? null;
+
+    $dest->commandname ??= $params["commandname"] ?? null;
+    $dest->commandproperty ??= $params["commandproperty"] ?? null;
+    $dest->commandkey ??= $params["commandkey"] ?? null;
+
+    $dest->argsname ??= $params["argsname"] ?? null;
+    $dest->argsproperty ??= $params["argsproperty"] ?? null;
+    $dest->argskey ??= $params["argskey"] ?? null;
+
+    $dest->autohelp ??= vbool::withn($params["autohelp"] ?? null);
+    $dest->autoremains ??= vbool::withn($params["autoremains"] ?? null);
+
+    # définition des options
     foreach ($defs as $def) {
       $argDefs[] = new ArgDef($def);
     }
-    foreach ($argDefs as $argDef) {
-      $argDef->processExtends();
-    }
-
-    $index = [];
-    foreach ($argDefs as $argDef) {
-      $options = $argDef->getOptions();
-      foreach ($options as $option) {
-        if (array_key_exists($option, $index)) {
-          $index[$option]->removeOption($option);
-        }
-        $index[$option] = $argDef;
-      }
-    }
-
-    foreach ($argDefs as $argDef) {
-      $argDef->processArgs();
-      $argDef->processAction();
-    }
-
-    $this->argDefs = $argDefs;
-    $this->index = $index;
   }
 
-  protected array $argDefs;
+  protected static function merge_parse_defs(SimpleArgDefs $dest, array $defs, ?array &$argDefs): void {
+    $defaults = $defs["defaults"] ?? null;
+    if ($defaults !== null) self::merge_parse_defs($dest, $defaults, $argDefs);
 
-  protected array $index;
+    self::parse_defs($dest, $defs, $argDefs);
 
-  function getArgDef(string $option): ?ArgDef {
-    return $this->index[$option] ?? null;
+    $merges = $defs["merges"] ?? null;
+    $merge = $defs["merge"] ?? null;
+    if ($merge !== null) $merges[] = $merge;
+    if ($merges !== null) self::merge_parse_defs($dest, $merges, $argDefs);
   }
 
+  public ?string $prefix = null;
+  public ?string $name = null;
+  public ?string $purpose = null;
+  public ?string $usage = null;
+  public ?string $description = null;
+  public ?string $suffix = null;
+
+  public ?string $commandname = null;
+  public ?string $commandproperty = null;
+  public ?string $commandkey = null;
+
+  public ?string $argsname = null;
+  public ?string $argsproperty = null;
+  public ?string $argskey = null;
+
+  public ?bool $autohelp = null;
+  public ?bool $autoremains = null;
+
   /**
    * consommer les arguments de $src en avançant l'index $srci et provisionner
    * $dest à partir de $desti. si $desti est plus grand que 0, celà veut dire
@@ -59,7 +79,7 @@ class ArgDefs {
    * disponible, ou jusqu'à la présence de '--'. Si $keepsep, l'argument '--'
    * est gardé dans la liste des arguments optionnels.
    */
-  private static function consume_args($src, &$srci, &$dest, $desti, $destmin, $destmax, bool $keepsep): int {
+  protected static function consume_args($src, &$srci, &$dest, $desti, $destmin, $destmax, bool $keepsep): int {
     $srcmax = count($src);
     # arguments obligatoires
     while ($desti < $destmin) {
@@ -88,158 +108,11 @@ class ArgDefs {
     return 0;
   }
 
-  private static function check_missing(?string $option, int $count) {
+  protected static function check_missing(?string $option, int $count) {
     if ($count > 0) {
       throw new ArgException("$option: nombre d'arguments insuffisant (manque $count)");
     }
   }
-
-  function normalize(array $args): array {
-    $i = 0;
-    $max = count($args);
-    $options = [];
-    $remains = [];
-    $parseOpts = true;
-    while ($i < $max) {
-      $arg = $args[$i++];
-      if (!$parseOpts) {
-        # le reste n'est que des arguments
-        $remains[] = $arg;
-        continue;
-      }
-      if ($arg === "--") {
-        # fin des options
-        $parseOpts = false;
-        continue;
-      }
-
-      if (substr($arg, 0, 2) === "--") {
-        #######################################################################
-        # option longue
-        $pos = strpos($arg, "=");
-        if ($pos !== false) {
-          # option avec valeur
-          $option = substr($arg, 0, $pos);
-          $value = substr($arg, $pos + 1);
-        } else {
-          # option sans valeur
-          $option = $arg;
-          $value = null;
-        }
-        /** @var ArgDef $argDef */
-        $argDef = $this->index[$option] ?? null;
-        if ($argDef === null) {
-          # chercher une correspondance
-          $len = strlen($option);
-          $candidates = [];
-          foreach (array_keys($this->index) as $candidate) {
-            if (substr($candidate, 0, $len) === $option) {
-              $candidates[] = $candidate;
-            }
-          }
-          switch (count($candidates)) {
-          case 0:
-            throw new ArgException("$option: option invalide");
-          case 1:
-            $option = $candidates[0];
-            break;
-          default:
-            $candidates = implode(", ", $candidates);
-            throw new ArgException("$option: option ambigue (les options possibles sont $candidates)");
-          }
-          $argDef = $this->index[$option];
-        }
-
-        if ($argDef->haveArgs) {
-          $minArgs = $argDef->minArgs;
-          $maxArgs = $argDef->maxArgs;
-          $values = [];
-          if ($value !== null) {
-            $values[] = $value;
-            $offset = 1;
-          } elseif ($minArgs == 0) {
-            # cas particulier: la première valeur doit être collée à l'option
-            # si $maxArgs == 1
-            $offset = $maxArgs == 1 ? 1 : 0;
-          } else {
-            $offset = 0;
-          }
-          $this->check_missing($option,
-            self::consume_args($args, $i, $values, $offset, $minArgs, $maxArgs, true));
-
-          if ($minArgs == 0 && $maxArgs == 1) {
-            # cas particulier: la première valeur doit être collée à l'option
-            if (count($values) > 0) {
-              $options[] = "$option=$values[0]";
-              $values = array_slice($values, 1);
-            } else {
-              $options[] = $option;
-            }
-          } else {
-            $options[] = $option;
-          }
-          $options = array_merge($options, $values);
-        } elseif ($value !== null) {
-          throw new ArgException("$option: cette option ne prend pas d'arguments");
-        } else {
-          $options[] = $option;
-        }
-
-      } elseif (substr($arg, 0, 1) === "-") {
-        #######################################################################
-        # option courte
-        $pos = 1;
-        $len = strlen($arg);
-        while ($pos < $len) {
-          $option = "-".substr($arg, $pos, 1);
-          /** @var ArgDef $argDef */
-          $argDef = $this->index[$option] ?? null;
-          if ($argDef === null) {
-            throw new ArgException("$option: option invalide");
-          }
-          if ($argDef->haveArgs) {
-            $minArgs = $argDef->minArgs;
-            $maxArgs = $argDef->maxArgs;
-            $values = [];
-            if ($len > $pos + 1) {
-              $values[] = substr($arg, $pos + 1);
-              $offset = 1;
-              $pos = $len;
-            } elseif ($minArgs == 0) {
-              # cas particulier: la première valeur doit être collée à l'option
-              # si $maxArgs == 1
-              $offset = $maxArgs == 1 ? 1 : 0;
-            } else {
-              $offset = 0;
-            }
-            $this->check_missing($option,
-              self::consume_args($args, $i, $values, $offset, $minArgs, $maxArgs, true));
-
-            if ($minArgs == 0 && $maxArgs == 1) {
-              # cas particulier: la première valeur doit être collée à l'option
-              if (count($values) > 0) {
-                $options[] = "$option$values[0]";
-                $values = array_slice($values, 1);
-              } else {
-                $options[] = $option;
-              }
-            } else {
-              $options[] = $option;
-            }
-            $options = array_merge($options, $values);
-          } else {
-            $options[] = $option;
-          }
-          $pos++;
-        }
-      } else {
-        #XXX implémenter les commandes
-
-        #######################################################################
-        # argument
-        $remains[] = $arg;
-      }
-    }
-    return array_merge($options, ["--"], $remains);
-  }
+  
+  abstract function normalize(array $args): array;
 }
diff --git a/src/app/cli/SimpleArgDefs.php b/src/app/cli/SimpleArgDefs.php
new file mode 100644
index 0000000..78fb85e
--- /dev/null
+++ b/src/app/cli/SimpleArgDefs.php
@@ -0,0 +1,198 @@
+<?php
+namespace nulib\app\cli;
+
+/**
+ * Class SimpleArgDefs: une définition simple des arguments et des options
+ * valides d'un programme: les commandes ne sont pas supportées, ni les suites
+ * de commandes
+ *
+ * i.e
+ *   -x --long            est supporté
+ *   cmd -a -b            n'est PAS supporté
+ *   cmd1 -x // cmd2 -y   n'est PAS supporté
+ */
+class SimpleArgDefs extends ArgDefs {
+  function __construct(array $defs) {
+    self::merge_parse_defs($this, $defs, $argDefs);
+
+    # calculer les héritages
+    foreach ($argDefs as $argDef) {
+      /** @var ArgDef $argDef */
+      $argDef->processParents($this);
+    }
+
+    # indexer les arguments
+    $index = [];
+    foreach ($argDefs as $argDef) {
+      $options = $argDef->getOptions();
+      foreach ($options as $option) {
+        if (array_key_exists($option, $index)) {
+          $index[$option]->removeOption($option);
+        }
+        $index[$option] = $argDef;
+      }
+    }
+
+    foreach ($argDefs as $argDef) {
+      $argDef->processArgs();
+      $argDef->processAction();
+    }
+
+    $this->index = $index;
+  }
+
+  protected array $index;
+
+  function getArgDef(string $option): ?ArgDef {
+    return $this->index[$option] ?? null;
+  }
+
+  function normalize(array $args): array {
+    $i = 0;
+    $max = count($args);
+    $options = [];
+    $remains = [];
+    $parseOpts = true;
+    while ($i < $max) {
+      $arg = $args[$i++];
+      if (!$parseOpts) {
+        # le reste n'est que des arguments
+        $remains[] = $arg;
+        continue;
+      }
+      if ($arg === "--") {
+        # fin des options
+        $parseOpts = false;
+        continue;
+      }
+
+      if (substr($arg, 0, 2) === "--") {
+        #######################################################################
+        # option longue
+        $pos = strpos($arg, "=");
+        if ($pos !== false) {
+          # option avec valeur
+          $option = substr($arg, 0, $pos);
+          $value = substr($arg, $pos + 1);
+        } else {
+          # option sans valeur
+          $option = $arg;
+          $value = null;
+        }
+        /** @var ArgDef $argDef */
+        $argDef = $this->index[$option] ?? null;
+        if ($argDef === null) {
+          # chercher une correspondance
+          $len = strlen($option);
+          $candidates = [];
+          foreach (array_keys($this->index) as $candidate) {
+            if (substr($candidate, 0, $len) === $option) {
+              $candidates[] = $candidate;
+            }
+          }
+          switch (count($candidates)) {
+          case 0:
+            throw new ArgException("$option: option invalide");
+          case 1:
+            $option = $candidates[0];
+            break;
+          default:
+            $candidates = implode(", ", $candidates);
+            throw new ArgException("$option: option ambigue (les options possibles sont $candidates)");
+          }
+          $argDef = $this->index[$option];
+        }
+
+        if ($argDef->haveArgs) {
+          $minArgs = $argDef->minArgs;
+          $maxArgs = $argDef->maxArgs;
+          $values = [];
+          if ($value !== null) {
+            $values[] = $value;
+            $offset = 1;
+          } elseif ($minArgs == 0) {
+            # cas particulier: la première valeur doit être collée à l'option
+            # si $maxArgs == 1
+            $offset = $maxArgs == 1 ? 1 : 0;
+          } else {
+            $offset = 0;
+          }
+          $this->check_missing($option,
+            self::consume_args($args, $i, $values, $offset, $minArgs, $maxArgs, true));
+
+          if ($minArgs == 0 && $maxArgs == 1) {
+            # cas particulier: la première valeur doit être collée à l'option
+            if (count($values) > 0) {
+              $options[] = "$option=$values[0]";
+              $values = array_slice($values, 1);
+            } else {
+              $options[] = $option;
+            }
+          } else {
+            $options[] = $option;
+          }
+          $options = array_merge($options, $values);
+        } elseif ($value !== null) {
+          throw new ArgException("$option: cette option ne prend pas d'arguments");
+        } else {
+          $options[] = $option;
+        }
+
+      } elseif (substr($arg, 0, 1) === "-") {
+        #######################################################################
+        # option courte
+        $pos = 1;
+        $len = strlen($arg);
+        while ($pos < $len) {
+          $option = "-".substr($arg, $pos, 1);
+          /** @var ArgDef $argDef */
+          $argDef = $this->index[$option] ?? null;
+          if ($argDef === null) {
+            throw new ArgException("$option: option invalide");
+          }
+          if ($argDef->haveArgs) {
+            $minArgs = $argDef->minArgs;
+            $maxArgs = $argDef->maxArgs;
+            $values = [];
+            if ($len > $pos + 1) {
+              $values[] = substr($arg, $pos + 1);
+              $offset = 1;
+              $pos = $len;
+            } elseif ($minArgs == 0) {
+              # cas particulier: la première valeur doit être collée à l'option
+              # si $maxArgs == 1
+              $offset = $maxArgs == 1 ? 1 : 0;
+            } else {
+              $offset = 0;
+            }
+            $this->check_missing($option,
+              self::consume_args($args, $i, $values, $offset, $minArgs, $maxArgs, true));
+
+            if ($minArgs == 0 && $maxArgs == 1) {
+              # cas particulier: la première valeur doit être collée à l'option
+              if (count($values) > 0) {
+                $options[] = "$option$values[0]";
+                $values = array_slice($values, 1);
+              } else {
+                $options[] = $option;
+              }
+            } else {
+              $options[] = $option;
+            }
+            $options = array_merge($options, $values);
+          } else {
+            $options[] = $option;
+          }
+          $pos++;
+        }
+      } else {
+        #XXX implémenter les commandes
+
+        #######################################################################
+        # argument
+        $remains[] = $arg;
+      }
+    }
+    return array_merge($options, ["--"], $remains);
+  }
+}
diff --git a/tests/app/cli/ArgDefTest.php b/tests/app/cli/ArgDefTest.php
index d420572..fb4dea6 100644
--- a/tests/app/cli/ArgDefTest.php
+++ b/tests/app/cli/ArgDefTest.php
@@ -10,7 +10,7 @@ class ArgDefTest extends TestCase {
     bool   $haveShortOptions, bool $haveLongOptions, bool $haveCommands,
     bool   $haveArgs, ?int $minArgs, ?int $maxArgs, ?string $argsdesc
   ) {
-    $argDef->processExtends();
+    $argDef->processParents();
     $argDef->processArgs();
     $argDef->processAction();
     self::assertSame($options, $argDef->getOptions());
@@ -23,50 +23,128 @@ class ArgDefTest extends TestCase {
     self::assertSame($argsdesc, $argDef->argsdesc, "argsdesc");
   }
 
-  function testBase() {
+  function testArgsNone() {
+    $argDef = new ArgDef(["-o"]);
+    self::assertArg($argDef,
+      ["-o"],
+      true, false, false,
+      false, 0, 0, "");
+
+    $argDef = new ArgDef(["--longo"]);
+    self::assertArg($argDef,
+      ["--longo"],
+      false, true, false,
+      false, 0, 0, "");
+
     $argDef = new ArgDef(["-o", "--longo"]);
     self::assertArg($argDef,
       ["-o", "--longo"],
       true, true, false,
       false, 0, 0, "");
+  }
 
+  function testArgsMandatory() {
     $argDef = new ArgDef(["-o:", "--longo"]);
     self::assertArg($argDef,
       ["-o", "--longo"],
       true, true, false,
       true, 1, 1, "VALUE");
 
+    $argDef = new ArgDef(["-a:", "-b:"]);
+    self::assertArg($argDef,
+      ["-a", "-b"],
+      true, false, false,
+      true, 1, 1, "VALUE");
+
+    $argDef = new ArgDef(["-a:", "-b::"]);
+    self::assertArg($argDef,
+      ["-a", "-b"],
+      true, false, false,
+      true, 1, 1, "VALUE");
+
+    $argDef = new ArgDef(["-a::", "-b:"]);
+    self::assertArg($argDef,
+      ["-a", "-b"],
+      true, false, false,
+      true, 1, 1, "VALUE");
+
+    $argDef = new ArgDef(["-o", "--longo", "args" => true]);
+    self::assertArg($argDef,
+      ["-o", "--longo"],
+      true, true, false,
+      true, 1, 1, "VALUE");
+
+    $argDef = new ArgDef(["-o", "--longo", "args" => 1]);
+    self::assertArg($argDef,
+      ["-o", "--longo"],
+      true, true, false,
+      true, 1, 1, "VALUE");
+
+    $argDef = new ArgDef(["-o", "--longo", "args" => "value"]);
+    self::assertArg($argDef,
+      ["-o", "--longo"],
+      true, true, false,
+      true, 1, 1, "VALUE");
+
+    $argDef = new ArgDef(["-o", "--longo", "args" => ["value"]]);
+    self::assertArg($argDef,
+      ["-o", "--longo"],
+      true, true, false,
+      true, 1, 1, "VALUE");
+  }
+
+  function testArgsOptional() {
     $argDef = new ArgDef(["-o::", "--longo"]);
     self::assertArg($argDef,
       ["-o", "--longo"],
       true, true, false,
       true, 0, 1, "[VALUE]");
 
-    $argDef = new ArgDef(["-o:", "--longo:"]);
+    $argDef = new ArgDef(["-o", "--longo", "args" => [["value"]]]);
     self::assertArg($argDef,
       ["-o", "--longo"],
       true, true, false,
-      true, 1, 1, "VALUE");
+      true, 0, 1, "[VALUE]");
 
-    $argDef = new ArgDef(["-o:", "--longo::"]);
+    $argDef = new ArgDef(["-o", "--longo", "args" => [[null]]]);
     self::assertArg($argDef,
       ["-o", "--longo"],
       true, true, false,
-      true, 1, 1, "VALUE");
+      true, 0, PHP_INT_MAX, "[VALUEs...]");
+
+    $argDef = new ArgDef(["-o", "--longo", "args" => ["value", null]]);
+    self::assertArg($argDef,
+      ["-o", "--longo"],
+      true, true, false,
+      true, 1, PHP_INT_MAX, "VALUE [VALUEs...]");
   }
 
-  function testExtends() {
-    $argDef = [
-      "extends" => [
-        "arg" => ["-o:", "--longo"],
+  function testParent() {
+    $BASE = ["-o:", "--longo"];
+
+    $argDef = new ArgDef([
+      "parent" => [
+        "arg" => $BASE,
         "add" => ["-a", "--longa"],
         "remove" => ["-o", "--longo"],
       ],
-    ];
-    $arg = new ArgDef($argDef);
-    self::assertArg($arg,
+    ]);
+    self::assertArg($argDef,
       ["-a", "--longa"],
       true, true, false,
       false, 0, 0, "");
+
+    $argDef = new ArgDef([
+      "parent" => [
+        "arg" => $BASE,
+        "add" => ["-a", "--longa"],
+        "remove" => ["-o", "--longo"],
+      ],
+      "-x",
+    ]);
+    self::assertArg($argDef,
+      ["-a", "--longa", "-x"],
+      true, true, false,
+      false, 0, 0, "");
   }
 }
diff --git a/tests/app/cli/ArgDefsTest.php b/tests/app/cli/SimpleArgDefsTest.php
similarity index 88%
rename from tests/app/cli/ArgDefsTest.php
rename to tests/app/cli/SimpleArgDefsTest.php
index 94cb19b..50d0a41 100644
--- a/tests/app/cli/ArgDefsTest.php
+++ b/tests/app/cli/SimpleArgDefsTest.php
@@ -3,9 +3,9 @@ namespace nulib\app\cli;
 
 use nur\t\TestCase;
 
-class ArgDefsTest extends TestCase {
-  function testBase() {
-    $argDefs = new ArgDefs([
+class SimpleArgDefsTest extends TestCase {
+  function testNormalize() {
+    $argDefs = new SimpleArgDefs([
       ["-a"],
       ["--longb"],
       ["-c", "--longc"],