diff --git a/src/file/csv/AbstractBuilder.php b/src/file/csv/AbstractBuilder.php
index 1ea4045..6336d36 100644
--- a/src/file/csv/AbstractBuilder.php
+++ b/src/file/csv/AbstractBuilder.php
@@ -16,6 +16,12 @@ abstract class AbstractBuilder extends TempStream implements IBuilder {
   /** @var ?array liste des colonnes à écrire */
   const HEADERS = null;
 
+  /**
+   * @var bool faut-il écrire les en-têtes, soit celles qui sont spécifiées,
+   * soit celles qui sont calculées à partir des clés de la première ligne
+   */
+  const USE_HEADERS = true;
+
   /** @var ?string nom du fichier téléchargé */
   const OUTPUT = null;
 
@@ -23,6 +29,7 @@ abstract class AbstractBuilder extends TempStream implements IBuilder {
     if ($output !== null) $params["output"] = $output;
     $this->schema = $params["schema"] ?? static::SCHEMA;
     $this->headers = $params["headers"] ?? static::HEADERS;
+    $this->useHeaders = $params["use_headers"] ?? static::USE_HEADERS;
     $rows = $params["rows"] ?? null;
     if (is_callable($rows)) $rows = $rows();
     $this->rows = $rows;
@@ -44,6 +51,8 @@ abstract class AbstractBuilder extends TempStream implements IBuilder {
 
   protected ?array $headers;
 
+  protected bool $useHeaders;
+
   protected ?iterable $rows;
 
   protected ?string $output;
@@ -53,7 +62,7 @@ abstract class AbstractBuilder extends TempStream implements IBuilder {
   protected ?array $cookArgs;
 
   protected function ensureHeaders(?array $row=null): void {
-    if ($this->headers !== null) return;
+    if ($this->headers !== null || !$this->useHeaders) return;
     if ($this->schema === null) $headers = null;
     else $headers = array_keys($this->schema);
     if ($headers === null && $row !== null) $headers = array_keys($row);
@@ -66,9 +75,11 @@ abstract class AbstractBuilder extends TempStream implements IBuilder {
 
   function writeHeaders(?array $headers=null): void {
     if ($this->wroteHeaders) return;
-    if ($headers !== null) $this->headers = $headers;
-    else $this->ensureHeaders();
-    if ($this->headers !== null) $this->_write($this->headers);
+    if ($this->useHeaders) {
+      if ($headers !== null) $this->headers = $headers;
+      else $this->ensureHeaders();
+      if ($this->headers !== null) $this->_write($this->headers);
+    }
     $this->wroteHeaders = true;
   }
 
diff --git a/src/file/csv/AbstractReader.php b/src/file/csv/AbstractReader.php
index 2c80209..4351169 100644
--- a/src/file/csv/AbstractReader.php
+++ b/src/file/csv/AbstractReader.php
@@ -5,13 +5,13 @@ use nur\sery\A;
 use nur\sery\php\time\Date;
 use nur\sery\php\time\DateTime;
 
-abstract class AbstractReader  implements IReader {
+abstract class AbstractReader implements IReader {
   const SCHEMA = null;
 
   const HEADERS = null;
 
   /** @var bool faut-il utiliser les en-têtes pour retourner des tableaux associatifs? */
-  const COOk_ROWS = true;
+  const USE_HEADERS = true;
 
   /** @var ?string nom du fichier depuis lequel lire */
   const INPUT = null;
@@ -40,7 +40,7 @@ abstract class AbstractReader  implements IReader {
     #
     $this->schema = $params["schema"] ?? static::SCHEMA;
     $this->headers = $params["headers"] ?? static::HEADERS;
-    $this->cookRows = $params["cook_rows"] ?? static::COOk_ROWS;
+    $this->useHeaders = $params["use_headers"] ?? static::USE_HEADERS;
     $this->input = $params["input"] ?? static::INPUT;
     $this->trim = boolval($params["trim"] ?? static::TRIM);
     $this->parseEmptyAsNull = boolval($params["empty_as_null"] ?? static::PARSE_EMPTY_AS_NULL);
@@ -52,7 +52,7 @@ abstract class AbstractReader  implements IReader {
 
   protected ?array $headers;
 
-  protected bool $cookRows;
+  protected bool $useHeaders;
 
   protected $input;
 
@@ -67,7 +67,7 @@ abstract class AbstractReader  implements IReader {
   protected int $isrc = 0, $idest = 0;
 
   protected function cookRow(array &$row): bool {
-    if (!$this->cookRows) return true;
+    if (!$this->useHeaders) return true;
     if ($this->isrc == 0) {
       # ligne d'en-tête
       $headers = $this->headers;
diff --git a/src/file/csv/IBuilder.php b/src/file/csv/IBuilder.php
index 393a724..1c98c3c 100644
--- a/src/file/csv/IBuilder.php
+++ b/src/file/csv/IBuilder.php
@@ -1,7 +1,7 @@
 <?php
 namespace nur\sery\file\csv;
 
-interface IBuilder {
+interface IBuilder extends \nur\sery\file\IReader {
   function writeHeaders(?array $headers=null): void;
 
   function write(?array $row): void;
diff --git a/src/file/csv/TAbstractBuilder.php b/src/file/csv/TAbstractBuilder.php
index a102570..06fb8d3 100644
--- a/src/file/csv/TAbstractBuilder.php
+++ b/src/file/csv/TAbstractBuilder.php
@@ -37,17 +37,15 @@ trait TAbstractBuilder {
     $output = $params["output"] ?? null;
     $ssType = null;
     if (is_string($output)) {
-      switch (path::ext($output)) {
-      case ".csv":
+      $ext = path::ext($output);
+      if ($output === "-" || $ext === ".csv") {
         $class = CsvBuilder::class;
-        break;
-      case ".ods":
+      } elseif ($ext === ".ods") {
         $ssType = "ods";
-        break;
-      case ".xlsx":
-      default:
+      } elseif ($ext === ".xlsx") {
+        $ssType = "xlsx";
+      } else {
         $ssType = "xlsx";
-        break;
       }
     }
     $params["ss_type"] = $ssType;
diff --git a/src/file/csv/TAbstractReader.php b/src/file/csv/TAbstractReader.php
index b2f56db..64d2595 100644
--- a/src/file/csv/TAbstractReader.php
+++ b/src/file/csv/TAbstractReader.php
@@ -36,17 +36,15 @@ trait TAbstractReader {
     $input = $params["input"] ?? null;
     $ssType = null;
     if (is_string($input)) {
-      switch (path::ext($input)) {
-      case ".csv":
+      $ext = path::ext($input);
+      if ($input === "-" || $ext === ".csv") {
         $class = CsvReader::class;
-        break;
-      case ".ods":
+      } elseif ($ext === ".ods") {
         $ssType = "ods";
-        break;
-      case ".xlsx":
-      default:
+      } elseif ($ext === ".xlsx") {
+        $ssType = "xlsx";
+      } else {
         $ssType = "xlsx";
-        break;
       }
     }
     $params["ss_type"] = $ssType;