Index: modules/field/field.crud.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.crud.inc,v
retrieving revision 1.22
diff -u -r1.22 field.crud.inc
--- modules/field/field.crud.inc	2 Aug 2009 11:24:21 -0000	1.22
+++ modules/field/field.crud.inc	8 Aug 2009 18:32:34 -0000
@@ -46,6 +46,8 @@
  * - cardinality (integer)
  *     The number of values the field can hold. Legal values are any
  *     positive integer or FIELD_CARDINALITY_UNLIMITED.
+ * - translatable (integer)
+ *     Whether the field is translatable
  * - locked (integer)
  *     TODO: undefined.
  * - module (string, read-only)
@@ -230,6 +232,7 @@
 
   $field += array(
     'cardinality' => 1,
+    'translatable' => FALSE,
     'locked' => FALSE,
     'settings' => array(),
   );
Index: modules/field/field.default.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.default.inc,v
retrieving revision 1.12
diff -u -r1.12 field.default.inc
--- modules/field/field.default.inc	2 Aug 2009 11:24:21 -0000	1.12
+++ modules/field/field.default.inc	8 Aug 2009 18:32:34 -0000
@@ -11,17 +11,17 @@
  * the corresponding field_attach_[operation]() function.
  */
 
-function field_default_extract_form_values($obj_type, $object, $field, $instance, &$items, $form, &$form_state) {
+function field_default_extract_form_values($obj_type, $object, $field, $instance, $language, &$items, $form, &$form_state) {
   $field_name = $field['field_name'];
 
-  if (isset($form_state['values'][$field_name])) {
-    $items = $form_state['values'][$field_name];
+  if (isset($form_state['values'][$field_name][$language])) {
+    $items = $form_state['values'][$field_name][$language];
     // Remove the 'value' of the 'add more' button.
     unset($items[$field_name . '_add_more']);
   }
 }
 
-function field_default_submit($obj_type, $object, $field, $instance, &$items, $form, &$form_state) {
+function field_default_submit($obj_type, $object, $field, $instance, $language, &$items, $form, &$form_state) {
   $field_name = $field['field_name'];
 
   // Reorder items to account for drag-n-drop reordering.
@@ -40,13 +40,18 @@
  * This can happen with programmatic saves, or on form-based creation where
  * the current user doesn't have 'edit' permission for the field.
  */
-function field_default_insert($obj_type, $object, $field, $instance, &$items) {
+function field_default_insert($obj_type, $object, $field, $instance, $language, &$items) {
   // _field_invoke() populates $items with an empty array if the $object has no
   // entry for the field, so we check on the $object itself.
-  if (!property_exists($object, $field['field_name']) && !empty($instance['default_value_function'])) {
+  // We also check that the current field translation is actually defined before 
+  // assigning it a default value, this way we ensure that only the intended languages
+  // get a default value, otherwise we could have default values for not yet open
+  // languages.
+  if (!empty($instance['default_value_function']) && (!property_exists($object, $field['field_name']) || 
+      (isset($object->{$field['field_name']}[$language]) && count($object->{$field['field_name']}[$language]) == 0))) {
     $function = $instance['default_value_function'];
     if (drupal_function_exists($function)) {
-      $items = $function($obj_type, $object, $field, $instance);
+      $items = $function($obj_type, $object, $field, $instance, $language);
     }
   }
 }
@@ -108,7 +113,7 @@
  *     ),
  *   );
  */
-function field_default_view($obj_type, $object, $field, $instance, $items, $build_mode) {
+function field_default_view($obj_type, $object, $field, $instance, $language, $items, $build_mode) {
   list($id, $vid, $bundle) = field_attach_extract_ids($obj_type, $object);
 
   $addition = array();
@@ -138,6 +143,7 @@
       '#label_display' => $label_display,
       '#build_mode' => $build_mode,
       '#single' => $single,
+      '#language' => $language,
       'items' => array(),
     );
 
@@ -173,7 +179,7 @@
   return $addition;
 }
 
-function field_default_prepare_translation($obj_type, $object, $field, $instance, &$items) {
+function field_default_prepare_translation($obj_type, $object, $field, $instance, $language, &$items) {
   $addition = array();
   if (isset($object->translation_source->$field['field_name'])) {
     $addition[$field['field_name']] = $object->translation_source->$field['field_name'];
Index: modules/field/field.info.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.info.inc,v
retrieving revision 1.11
diff -u -r1.11 field.info.inc
--- modules/field/field.info.inc	2 Aug 2009 11:24:21 -0000	1.11
+++ modules/field/field.info.inc	8 Aug 2009 18:32:34 -0000
@@ -117,6 +117,7 @@
           // Provide defaults.
           $fieldable_info += array(
             'cacheable' => TRUE,
+            'translation_handlers' => array(),
             'bundles' => array(),
           );
           $fieldable_info['object keys'] += array(
Index: modules/field/field.attach.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.attach.inc,v
retrieving revision 1.33
diff -u -r1.33 field.attach.inc
--- modules/field/field.attach.inc	16 Jul 2009 10:30:12 -0000	1.33
+++ modules/field/field.attach.inc	8 Aug 2009 18:32:33 -0000
@@ -166,6 +166,7 @@
   // Merge default options.
   $default_options = array(
     'default' => FALSE,
+    'language' => NULL
   );
   $options += $default_options;
 
@@ -178,32 +179,38 @@
     // When in 'single field' mode, only act on the specified field.
     if (empty($options['field_name']) || $options['field_name'] == $field_name) {
       $field = field_info_field($field_name);
+      $field_translations = array();
+      $suggested_languages = empty($options['language']) ? NULL : array($options['language']);
 
-      // Extract the field values into a separate variable, easily accessed by
-      // hook implementations.
-      $items = isset($object->$field_name) ? $object->$field_name : array();
+      // Initialize field translations according to the available languages.
+      foreach (field_multilingual_available_languages($obj_type, $field, $suggested_languages) as $language) {
+        $field_translations[$language] = isset($object->{$field_name}[$language]) ? $object->{$field_name}[$language] : array();
+      }
 
       // Invoke the field hook and collect results.
       $function = $options['default'] ? 'field_default_' . $op : $field['module'] . '_field_' . $op;
       if (drupal_function_exists($function)) {
-        $result = $function($obj_type, $object, $field, $instance, $items, $a, $b);
-        if (isset($result)) {
-          // For hooks with array results, we merge results together.
-          // For hooks with scalar results, we collect results in an array.
-          if (is_array($result)) {
-            $return = array_merge($return, $result);
+        // Iterate over all the field translations.
+        foreach ($field_translations as $language => $items) {
+          $result = $function($obj_type, $object, $field, $instance, $language, $items, $a, $b);
+          if (isset($result)) {
+            // For hooks with array results, we merge results together.
+            // For hooks with scalar results, we collect results in an array.
+            if (is_array($result)) {
+              $return = array_merge($return, $result);
+            }
+            else {
+              $return[] = $result;
+            }
           }
-          else {
-            $return[] = $result;
+
+          // Populate $items back in the field values, but avoid replacing missing
+          // fields with an empty array (those are not equivalent on update).
+          if ($items !== array() || isset($object->{$field_name}[$language])) {
+            $object->{$field_name}[$language] = $items;
           }
         }
       }
-
-      // Populate field values back in the object, but avoid replacing missing
-      // fields with an empty array (those are not equivalent on update).
-      if ($items !== array() || property_exists($object, $field_name)) {
-        $object->$field_name = $items;
-      }
     }
   }
 
@@ -248,6 +255,7 @@
   // Merge default options.
   $default_options = array(
     'default' => FALSE,
+    'language' => NULL
   );
   $options += $default_options;
 
@@ -271,10 +279,11 @@
         }
         // Group the corresponding instances and objects.
         $grouped_instances[$field_name][$id] = $instance;
-        $grouped_objects[$field_name][$id] = $objects[$id];
-        // Extract the field values into a separate variable, easily accessed
-        // by hook implementations.
-        $grouped_items[$field_name][$id] = isset($object->$field_name) ? $object->$field_name : array();
+        $grouped_objects[$field_name][$id] = &$objects[$id];
+        $suggested_languages = empty($options['language']) ? NULL : array($options['language']);
+        foreach (field_multilingual_available_languages($obj_type, $fields[$field_name], $suggested_languages) as $language) {
+          $grouped_items[$field_name][$language][$id] = isset($object->{$field_name}[$language]) ? $object->{$field_name}[$language] : array();
+        }
       }
     }
     // Initialize the return value for each object.
@@ -285,17 +294,20 @@
   foreach ($fields as $field_name => $field) {
     $function = $options['default'] ? 'field_default_' . $op : $field['module'] . '_field_' . $op;
     if (drupal_function_exists($function)) {
-      $results = $function($obj_type, $grouped_objects[$field_name], $field, $grouped_instances[$field_name], $grouped_items[$field_name], $a, $b);
-      if (isset($results)) {
-        // Collect results by object.
-        // For hooks with array results, we merge results together.
-        // For hooks with scalar results, we collect results in an array.
-        foreach ($results as $id => $result) {
-          if (is_array($result)) {
-            $return[$id] = array_merge($return[$id], $result);
-          }
-          else {
-            $return[$id][] = $result;
+      // Iterate over all the field translations.
+      foreach ($grouped_items[$field_name] as $language => $items) {
+        $results = $function($obj_type, $grouped_objects[$field_name], $field, $grouped_instances[$field_name], $language, $grouped_items[$field_name][$language], $a, $b);
+        if (isset($results)) {
+          // Collect results by object.
+          foreach ($results as $id => $result) {
+            // For hooks with array results, we merge results together.
+            // For hooks with scalar results, we collect results in an array.
+            if (is_array($result)) {
+              $return[$id] = array_merge($return[$id], $result);
+            }
+            else {
+              $return[$id][] = $result;
+            }
           }
         }
       }
@@ -304,8 +316,10 @@
     // Populate field values back in the objects, but avoid replacing missing
     // fields with an empty array (those are not equivalent on update).
     foreach ($grouped_objects[$field_name] as $id => $object) {
-      if ($grouped_items[$field_name][$id] !== array() || property_exists($object, $field_name)) {
-        $object->$field_name = $grouped_items[$field_name][$id];
+      foreach ($grouped_items[$field_name] as $language => $items) {
+        if ($grouped_items[$field_name][$language][$id] !== array() || isset($object->{$field_name}[$language])) {
+          $object->{$field_name}[$language] = $grouped_items[$field_name][$language][$id];
+        }
       }
     }
   }
@@ -353,12 +367,17 @@
  *   The form structure to fill in.
  * @param $form_state
  *   An associative array containing the current state of the form.
+ * @param $language
+ *   TODO: The are two ways to enter field values: predefined language and
+ *   user provided language [...]
  *
  * TODO : document the resulting $form structure, like we do for
  * field_attach_view().
  */
-function field_attach_form($obj_type, $object, &$form, &$form_state) {
-  $form += (array) _field_invoke_default('form', $obj_type, $object, $form, $form_state);
+function field_attach_form($obj_type, $object, &$form, &$form_state, $language = NULL) {
+  // If no language is provided use the default site language.
+  $options = array('language' => field_multilingual_valid_language($language));
+  $form += (array) _field_invoke_default('form', $obj_type, $object, $form, $form_state, $options);
 
   // Let other modules make changes to the form.
   foreach (module_implements('field_attach_form') as $module) {
@@ -880,17 +899,53 @@
  * @return
  *   A structured content array tree for drupal_render().
  */
-function field_attach_view($obj_type, $object, $build_mode = 'full') {
+function field_attach_view($obj_type, $object, $build_mode = 'full', $language = NULL) {
+  // If no language is provided use the current UI language.
+  $options = array('language' => field_multilingual_valid_language($language, FALSE));
+
   // Let field modules sanitize their data for output.
-  _field_invoke('sanitize', $obj_type, $object);
+  _field_invoke('sanitize', $obj_type, $object, $null, $null, $options);
 
-  $output = _field_invoke_default('view', $obj_type, $object, $build_mode);
+  $output = _field_invoke_default('view', $obj_type, $object, $build_mode, $null, $options);
 
   // Let other modules make changes after rendering the view.
   drupal_alter('field_attach_view', $output, $obj_type, $object, $build_mode);
 
   return $output;
+}
+
+/**
+ * Populate the template variables with the field values available for rendering.
+ *
+ * The $variables array will be populated with all the field instance values associated
+ * with the given entity type, keyed by field name; in case of translatable fields the
+ * language currently chosen for display will be selected.
+ *
+ * @param $obj_type
+ *   The type of $object; e.g. 'node' or 'user'.
+ * @param $object
+ *   The object with fields to render.
+ * @param $element
+ *   The structured array containing the values ready for rendering.
+ * @param $variables
+ *   The variables array is passed by reference and will be populated with field values.
+ */
+function field_attach_preprocess($obj_type, $object, $element, &$variables) {
+  list(, , $bundle) = field_attach_extract_ids($obj_type, $object);
 
+  foreach (field_info_instances($bundle) as $instance) {
+    $field_name = $instance['field_name'];
+    if (isset($element[$field_name]['#language'])) {
+      $language = $element[$field_name]['#language'];
+      $variables[$field_name] = isset($object->{$field_name}[$language]) ? $object->{$field_name}[$language] : NULL;
+    }
+  }
+
+  // Let other modules make changes to the form.
+  foreach (module_implements('field_attach_preprocess') as $module) {
+    $function = $module . '_field_attach_preprocess';
+    $function($obj_type, $object, $element, $variables);
+  }
 }
 
 /**
Index: modules/field/field.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.module,v
retrieving revision 1.21
diff -u -r1.21 field.module
--- modules/field/field.module	2 Aug 2009 11:24:21 -0000	1.21
+++ modules/field/field.module	8 Aug 2009 18:32:35 -0000
@@ -12,6 +12,7 @@
  */
 require(DRUPAL_ROOT . '/modules/field/field.crud.inc');
 require(DRUPAL_ROOT . '/modules/field/field.info.inc');
+require(DRUPAL_ROOT . '/modules/field/field.multilingual.inc');
 require(DRUPAL_ROOT . '/modules/field/field.attach.inc');
 
 /**
@@ -64,6 +65,12 @@
 define('FIELD_CARDINALITY_UNLIMITED', -1);
 
 /**
+ * The language code assigned to untranslatable fields. 
+ * (ISO639-2 No linguistic content / Not applicable)
+ */
+define('FIELD_LANGUAGE_NONE', 'zxx');
+
+/**
  * TODO
  */
 define('FIELD_BEHAVIOR_NONE', 0x0001);
@@ -605,6 +612,8 @@
     'label' => check_plain(t($instance['label'])),
     'label_display' => $element['#label_display'],
     'field_empty' => $field_empty,
+    'field_language' => $element['#language'],
+    'field_translatable' => $field['translatable'],
     'template_files' => array(
       'field',
       'field-' . $element['#field_name'],
Index: modules/field/field.form.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.form.inc,v
retrieving revision 1.12
diff -u -r1.12 field.form.inc
--- modules/field/field.form.inc	27 Jul 2009 20:19:20 -0000	1.12
+++ modules/field/field.form.inc	8 Aug 2009 18:32:34 -0000
@@ -9,7 +9,7 @@
 /**
  * Create a separate form element for each field.
  */
-function field_default_form($obj_type, $object, $field, $instance, $items, &$form, &$form_state, $get_delta = NULL) {
+function field_default_form($obj_type, $object, $field, $instance, $language, $items, &$form, &$form_state, $get_delta = NULL) {
   // This could be called with no object, as when a UI module creates a
   // dummy form to set default values.
   if ($object) {
@@ -52,7 +52,7 @@
   // and we are displaying an individual element, process the multiple value
   // form.
   if (!isset($get_delta) && field_behaviors_widget('multiple values', $instance) == FIELD_BEHAVIOR_DEFAULT) {
-    $form_element = field_multiple_value_form($field, $instance, $items, $form, $form_state);
+    $form_element = field_multiple_value_form($field, $instance, $language, $items, $form, $form_state);
   }
   // If the widget is handling multiple values (e.g Options),
   // or if we are displaying an individual element, just get a single form
@@ -93,7 +93,15 @@
       '#weight' => $instance['weight'],
     );
 
-    $addition[$field['field_name']] = array_merge($form_element, $defaults);
+    $form_element = array_merge($form_element, $defaults);
+
+    $addition[$field['field_name']] = array(
+      '#tree' => TRUE,
+      '#weight' => $form_element['#weight'],
+      '#language' => $language,
+      $language => $form_element,
+    );
+
     $form['#fields'][$field['field_name']]['form_path'] = array($field['field_name']);
   }
 
@@ -108,7 +116,7 @@
  * - AHAH-'add more' button
  * - drag-n-drop value reordering
  */
-function field_multiple_value_form($field, $instance, $items, &$form, &$form_state) {
+function field_multiple_value_form($field, $instance, $language, $items, &$form, &$form_state) {
   $field = field_info_field($instance['field_name']);
   $field_name = $field['field_name'];
 
@@ -202,9 +210,11 @@
         '#field_name' => $field_name,
         '#bundle' => $instance['bundle'],
         '#attributes' => array('class' => 'field-add-more-submit'),
+        '#language' => $language,
       );
     }
   }
+
   return $form_element;
 }
 
@@ -281,9 +291,9 @@
 /**
  * Transfer field-level validation errors to widgets.
  */
-function field_default_form_errors($obj_type, $object, $field, $instance, $items, $form, $errors) {
+function field_default_form_errors($obj_type, $object, $field, $instance, $language, $items, $form, $errors) {
   $field_name = $field['field_name'];
-  if (!empty($errors[$field_name])) {
+  if (!empty($errors[$field_name][$language])) {
     $function = $instance['widget']['module'] . '_field_widget_error';
     $function_exists = drupal_function_exists($function);
 
@@ -295,10 +305,10 @@
     }
 
     $multiple_widget = field_behaviors_widget('multiple values', $instance) != FIELD_BEHAVIOR_DEFAULT;
-    foreach ($errors[$field_name] as $delta => $delta_errors) {
+    foreach ($errors[$field_name][$language] as $delta => $delta_errors) {
       // For multiple single-value widgets, pass errors by delta.
       // For a multiple-value widget, all errors are passed to the main widget.
-      $error_element = $multiple_widget ? $element : $element[$delta];
+      $error_element = $multiple_widget ? $element[$language] : $element[$language][$delta];
       foreach ($delta_errors as $error) {
         if ($function_exists) {
           $function($error_element, $error);
@@ -325,8 +335,9 @@
 
     // Make the changes we want to the form state.
     $field_name = $form_state['clicked_button']['#field_name'];
+    $language = $form_state['clicked_button']['#language'];
     if ($form_state['values'][$field_name . '_add_more']) {
-      $form_state['field_item_count'][$field_name] = count($form_state['values'][$field_name]);
+      $form_state['field_item_count'][$field_name] = count($form_state['values'][$field_name][$language]);
     }
   }
 }
@@ -358,7 +369,7 @@
   $instance = $form['#fields'][$field_name]['instance'];
   $form_path = $form['#fields'][$field_name]['form_path'];
   if ($field['cardinality'] != FIELD_CARDINALITY_UNLIMITED) {
-    // Ivnalid
+    // Invalid
     $invalid = TRUE;
   }
 
@@ -388,19 +399,25 @@
   // Reset cached ids, so that they don't affect the actual form we output.
   drupal_static_reset('form_clean_id');
 
+  // Ensure that a valid language is provided.
+  $language = key($_POST[$field_name]);
+  if ($language != FIELD_LANGUAGE_NONE) { 
+    $language = field_multilingual_valid_language($language);
+  }
+
   // Sort the $form_state['values'] we just built *and* the incoming $_POST data
   // according to d-n-d reordering.
-  unset($form_state['values'][$field_name][$field['field_name'] . '_add_more']);
-  foreach ($_POST[$field_name] as $delta => $item) {
-    $form_state['values'][$field_name][$delta]['_weight'] = $item['_weight'];
+  unset($form_state['values'][$field_name][$language][$field['field_name'] . '_add_more']);
+  foreach ($_POST[$field_name][$language] as $delta => $item) {
+    $form_state['values'][$field_name][$language][$delta]['_weight'] = $item['_weight'];
   }
-  $form_state['values'][$field_name] = _field_sort_items($field, $form_state['values'][$field_name]);
-  $_POST[$field_name]                = _field_sort_items($field, $_POST[$field_name]);
+  $form_state['values'][$field_name][$language] = _field_sort_items($field, $form_state['values'][$field_name][$language]);
+  $_POST[$field_name][$language]                = _field_sort_items($field, $_POST[$field_name][$language]);
 
   // Build our new form element for the whole field, asking for one more element.
-  $form_state['field_item_count'] = array($field_name => count($_POST[$field_name]) + 1);
-  $items = $form_state['values'][$field_name];
-  $form_element = field_default_form(NULL, NULL, $field, $instance, $items, $form, $form_state);
+  $form_state['field_item_count'] = array($field_name => count($_POST[$field_name][$language]) + 1);
+  $items = $form_state['values'][$field_name][$language];
+  $form_element = field_default_form(NULL, NULL, $field, $instance, $language, $items, $form, $form_state);
   // Let other modules alter it.
   drupal_alter('form', $form_element, array(), 'field_add_more_js');
 
@@ -417,8 +434,8 @@
 
   // Build the new form against the incoming $_POST values so that we can
   // render the new element.
-  $delta = max(array_keys($_POST[$field_name])) + 1;
-  $_POST[$field_name][$delta]['_weight'] = $delta;
+  $delta = max(array_keys($_POST[$field_name][$language])) + 1;
+  $_POST[$field_name][$language][$delta]['_weight'] = $delta;
   $form_state = form_state_defaults();
   $form_state['input'] = $_POST;
   $form = form_builder($_POST['form_id'], $form, $form_state);
Index: modules/field/field.info
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.info,v
retrieving revision 1.4
diff -u -r1.4 field.info
--- modules/field/field.info	8 Jun 2009 09:23:51 -0000	1.4
+++ modules/field/field.info	8 Aug 2009 18:32:34 -0000
@@ -9,6 +9,7 @@
 files[] = field.crud.inc
 files[] = field.info.inc
 files[] = field.default.inc
+files[] = field.multilingual.inc
 files[] = field.attach.inc
 files[] = field.form.inc
 files[] = field.test
Index: modules/field/field.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.install,v
retrieving revision 1.9
diff -u -r1.9 field.install
--- modules/field/field.install	28 May 2009 10:05:32 -0000	1.9
+++ modules/field/field.install	8 Aug 2009 18:32:34 -0000
@@ -63,6 +63,12 @@
         'not null' => TRUE,
         'default' => 0,
       ),
+      'translatable' => array(
+        'type' => 'int',
+        'size' => 'tiny',
+        'not null' => TRUE,
+        'default' => 0,
+      ),
       'active' => array(
         'type' => 'int',
         'size' => 'tiny',
Index: modules/field/theme/field.tpl.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/theme/field.tpl.php,v
retrieving revision 1.3
diff -u -r1.3 field.tpl.php
--- modules/field/theme/field.tpl.php	22 Jun 2009 09:10:04 -0000	1.3
+++ modules/field/theme/field.tpl.php	8 Aug 2009 18:32:35 -0000
@@ -18,6 +18,8 @@
  * - $label: The item label.
  * - $label_display: Position of label display, inline, above, or hidden.
  * - $field_empty: Whether the field has any valid value.
+ * - $field_language: The field language.
+ * - $field_translatable: Whether the field is translatable or not.
  *
  * Each $item in $items contains:
  * - 'view' - the themed view for that item
Index: modules/node/node.tpl.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.tpl.php,v
retrieving revision 1.19
diff -u -r1.19 node.tpl.php
--- modules/node/node.tpl.php	6 Aug 2009 05:05:59 -0000	1.19
+++ modules/node/node.tpl.php	8 Aug 2009 18:32:36 -0000
@@ -58,6 +58,13 @@
  * - $is_front: Flags true when presented in the front page.
  * - $logged_in: Flags true when the current user is a logged-in member.
  * - $is_admin: Flags true when the current user is an administrator.
+ * 
+ * Field variables: for each field instance attached to the node a corresponding
+ * variable is defined, e.g. $node->body becomes $body. When needing to access
+ * the field raw values developers/themers are strongly encouraged to use these
+ * variables, otherwise they will have to explicitly specify the desired field 
+ * language, e.g. $node->body['en'], thus overriding any language negotiation
+ * rule previously applied.
  *
  * @see template_preprocess()
  * @see template_preprocess_node()
Index: modules/node/node.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.pages.inc,v
retrieving revision 1.73
diff -u -r1.73 node.pages.inc
--- modules/node/node.pages.inc	4 Aug 2009 06:44:48 -0000	1.73
+++ modules/node/node.pages.inc	8 Aug 2009 18:32:36 -0000
@@ -284,7 +284,7 @@
   $form['#theme'] = array($node->type . '_node_form', 'node_form');
 
   $form['#builder_function'] = 'node_form_submit_build_node';
-  field_attach_form('node', $node, $form, $form_state);
+  field_attach_form('node', $node, $form, $form_state, $node->language);
 
   return $form;
 }
Index: modules/field/modules/field_sql_storage/field_sql_storage.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/modules/field_sql_storage/field_sql_storage.module,v
retrieving revision 1.17
diff -u -r1.17 field_sql_storage.module
--- modules/field/modules/field_sql_storage/field_sql_storage.module	15 Jul 2009 17:55:18 -0000	1.17
+++ modules/field/modules/field_sql_storage/field_sql_storage.module	8 Aug 2009 18:32:35 -0000
@@ -144,8 +144,16 @@
         'not null' => TRUE,
         'description' => 'The sequence number for this data item, used for multi-value fields',
       ),
+      // TODO: Consider an integer field for 'language'.
+      'language' => array(
+        'type' => 'varchar',
+        'length' => 32,
+        'not null' => TRUE,
+        'default' => '',
+        'description' => 'The language for this data item.',
+      ),
     ),
-    'primary key' => array('etid', 'entity_id', 'deleted', 'delta'),
+    'primary key' => array('etid', 'entity_id', 'deleted', 'delta', 'language'),
     // TODO : index on 'bundle'
   );
 
@@ -169,7 +177,7 @@
   $revision = $current;
   $revision['description'] = "Revision archive storage for {$deleted}field {$field['id']} ({$field['field_name']})";
   $revision['revision_id']['description'] = 'The entity revision id this data is attached to';
-  $revision['primary key'] = array('etid', 'revision_id', 'deleted', 'delta');
+  $revision['primary key'] = array('etid', 'revision_id', 'deleted', 'delta', 'language');
 
   return array(
     _field_sql_storage_tablename($field) => $current,
@@ -215,7 +223,7 @@
       if (!isset($skip_fields[$field_name]) && (!isset($options['field_name']) || $options['field_name'] == $instance['field_name'])) {
         $objects[$id]->{$field_name} = array();
         $field_ids[$field_name][] = $load_current ? $id : $vid;
-        $delta_count[$id][$field_name] = 0;
+        $delta_count[$id][$field_name] = array();
       }
     }
   }
@@ -229,12 +237,17 @@
       ->condition('etid', $etid)
       ->condition($load_current ? 'entity_id' : 'revision_id', $ids, 'IN')
       ->condition('deleted', 0)
+      ->condition('language', field_multilingual_available_languages($obj_type, $field), 'IN')
       ->orderBy('delta');
 
     $results = $query->execute();
 
     foreach ($results as $row) {
-      if ($field['cardinality'] == FIELD_CARDINALITY_UNLIMITED || $delta_count[$row->entity_id][$field_name] < $field['cardinality']) {
+      if (!isset($delta_count[$row->entity_id][$field_name][$row->language])) {
+        $delta_count[$row->entity_id][$field_name][$row->language] = 0;
+      }
+    
+      if ($field['cardinality'] == FIELD_CARDINALITY_UNLIMITED || $delta_count[$row->entity_id][$field_name][$row->language] < $field['cardinality']) {
         $item = array();
         // For each column declared by the field, populate the item
         // from the prefixed database column.
@@ -244,8 +257,8 @@
         }
 
         // Add the item to the field values for the entity.
-        $objects[$row->entity_id]->{$field_name}[] = $item;
-        $delta_count[$row->entity_id][$field_name]++;
+        $objects[$row->entity_id]->{$field_name}[$row->language][] = $item;
+        $delta_count[$row->entity_id][$field_name][$row->language]++;
       }
     }
   }
@@ -275,17 +288,33 @@
     // Function property_exists() is slower, so we catch the more frequent cases
     // where it's an empty array with the faster isset().
     if (isset($object->$field_name) || property_exists($object, $field_name)) {
+      $available_languages = field_multilingual_available_languages($obj_type, $field);
+      $available_translations = is_array($object->$field_name) ? array_intersect($available_languages, array_keys($object->$field_name)) : FALSE;
+
       // Delete and insert, rather than update, in case a value was added.
-      if ($op == FIELD_STORAGE_UPDATE) {
-        db_delete($table_name)->condition('etid', $etid)->condition('entity_id', $id)->execute();
+      // If no translation is available, empty the field for all the available languages.
+      if ($op == FIELD_STORAGE_UPDATE && count($available_translations)) {
+        $languages = empty($object->$field_name) ? $available_languages : $available_translations;
+
+        db_delete($table_name)
+          ->condition('etid', $etid)
+          ->condition('entity_id', $id)
+          ->condition('language', $languages, 'IN')
+          ->execute();
+
         if (isset($vid)) {
-          db_delete($revision_name)->condition('etid', $etid)->condition('entity_id', $id)->condition('revision_id', $vid)->execute();
+          db_delete($revision_name)
+            ->condition('etid', $etid)
+            ->condition('entity_id', $id)
+            ->condition('revision_id', $vid)
+            ->condition('language', $languages, 'IN')
+            ->execute();
         }
       }
 
-      if ($object->$field_name) {
+      if (!empty($available_translations)) {
         // Prepare the multi-insert query.
-        $columns = array('etid', 'entity_id', 'revision_id', 'bundle', 'delta');
+        $columns = array('etid', 'entity_id', 'revision_id', 'bundle', 'delta', 'language');
         foreach ($field['columns'] as $column => $attributes) {
           $columns[] = _field_sql_storage_columnname($field_name, $column);
         }
@@ -294,25 +323,30 @@
           $revision_query = db_insert($revision_name)->fields($columns);
         }
 
-        $delta_count = 0;
-        foreach ($object->$field_name as $delta => $item) {
-          $record = array(
-            'etid' => $etid,
-            'entity_id' => $id,
-            'revision_id' => $vid,
-            'bundle' => $bundle,
-            'delta' => $delta,
-          );
-          foreach ($field['columns'] as $column => $attributes) {
-            $record[_field_sql_storage_columnname($field_name, $column)] = isset($item[$column]) ? $item[$column] : NULL;
-          }
-          $query->values($record);
-          if (isset($vid)) {
-            $revision_query->values($record);
-          }
-
-          if ($field['cardinality'] != FIELD_CARDINALITY_UNLIMITED && ++$delta_count == $field['cardinality']) {
-            break;
+        foreach ($available_translations as $language) {
+          if ($items = $object->{$field_name}[$language]) {
+            $delta_count = 0;
+            foreach ($items as $delta => $item) {
+              $record = array(
+                'etid' => $etid,
+                'entity_id' => $id,
+                'revision_id' => $vid,
+                'bundle' => $bundle,
+                'delta' => $delta,
+                'language' => $language,
+              );
+              foreach ($field['columns'] as $column => $attributes) {
+                $record[_field_sql_storage_columnname($field_name, $column)] = isset($item[$column]) ? $item[$column] : NULL;
+              }
+              $query->values($record);
+              if (isset($vid)) {
+                $revision_query->values($record);
+              }
+
+              if ($field['cardinality'] != FIELD_CARDINALITY_UNLIMITED && ++$delta_count == $field['cardinality']) {
+                break;
+              }
+            }
           }
         }
 
Index: modules/user/user-profile.tpl.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/user/user-profile.tpl.php,v
retrieving revision 1.10
diff -u -r1.10 user-profile.tpl.php
--- modules/user/user-profile.tpl.php	13 Jul 2009 21:09:54 -0000	1.10
+++ modules/user/user-profile.tpl.php	8 Aug 2009 18:32:36 -0000
@@ -15,6 +15,13 @@
  * is provided which contains data on the user's history. Other data can be
  * included by modules. $user_profile['user_picture'] is available
  * for showing the account picture.
+ * 
+ * Field variables: for each field instance attached to the user a corresponding
+ * variable is defined, e.g. $user->field_example becomes $field_example. When 
+ * needing to access the field raw values developers/themers are strongly encouraged 
+ * to use these variables, otherwise they will have to explicitly specify the desired 
+ * field language, e.g. $user->field_example['en'], thus overriding any language 
+ * negotiation rule previously applied.
  *
  * @see user-profile-category.tpl.php
  *   Where the html is handled for the group.
Index: modules/field/modules/text/text.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/modules/text/text.module,v
retrieving revision 1.17
diff -u -r1.17 text.module
--- modules/field/modules/text/text.module	4 Aug 2009 06:38:56 -0000	1.17
+++ modules/field/modules/text/text.module	8 Aug 2009 18:32:35 -0000
@@ -135,7 +135,7 @@
  * - 'text_value_max_length': The value exceeds the maximum length.
  * - 'text_summary_max_length': The summary exceeds the maximum length.
  */
-function text_field_validate($obj_type, $object, $field, $instance, $items, &$errors) {
+function text_field_validate($obj_type, $object, $field, $instance, $language, $items, &$errors) {
   foreach ($items as $delta => $item) {
     foreach (array('value' => t('full text'), 'summary' => t('summary')) as $column => $desc) {
       if (!empty($item[$column])) {
@@ -148,7 +148,7 @@
               $message = t('%name: the summary may not be longer than %max characters.', array('%name' => $instance['label'], '%max' => $field['settings']['max_length']));
               break;
           }
-          $errors[$field['field_name']][$delta][] = array(
+          $errors[$field['field_name']][$language][$delta][] = array(
             'error' => "text_{$column}_length",
             'message' => $message,
           );
@@ -166,9 +166,7 @@
  * separately.
  * @see text_field_sanitize().
  */
-function text_field_load($obj_type, $objects, $field, $instances, &$items) {
-  global $language;
-
+function text_field_load($obj_type, $objects, $field, $instances, $language, &$items) {
   foreach ($objects as $id => $object) {
     foreach ($items[$id] as $delta => $item) {
       if (!empty($instances[$id]['settings']['text_processing'])) {
@@ -176,10 +174,9 @@
         // handled by text_field_sanitize().
         $format = $item['format'];
         if (filter_format_allowcache($format)) {
-          $lang = isset($object->language) ? $object->language : $language->language;
-          $items[$id][$delta]['safe'] = isset($item['value']) ? check_markup($item['value'], $format, $lang, FALSE, FALSE) : '';
+          $items[$id][$delta]['safe'] = isset($item['value']) ? check_markup($item['value'], $format, $language, FALSE, FALSE) : '';
           if ($field['type'] == 'text_with_summary') {
-            $items[$id][$delta]['safe_summary'] = isset($item['summary']) ? check_markup($item['summary'], $format, $lang, FALSE, FALSE) : '';
+            $items[$id][$delta]['safe_summary'] = isset($item['summary']) ? check_markup($item['summary'], $format, $language, FALSE, FALSE) : '';
           }
         }
       }
@@ -198,7 +195,7 @@
  *
  * @see text_field_load()
  */
-function text_field_sanitize($obj_type, $object, $field, $instance, &$items) {
+function text_field_sanitize($obj_type, $object, $field, $instance, $language, &$items) {
   global $language;
   foreach ($items as $delta => $item) {
     // Only sanitize items which were not already processed inside
Index: modules/field/field.multilingual.inc
===================================================================
RCS file: modules/field/field.multilingual.inc
diff -N modules/field/field.multilingual.inc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ modules/field/field.multilingual.inc	1 Jan 1970 00:00:00 -0000
@@ -0,0 +1,117 @@
+<?php
+// $Id$
+/**
+ * @file
+ * Multilingual fields API helper functions.
+ */
+
+/**
+ * Collect the available languages for the given entity type and field.
+ *
+ * If an entity has translation handler and the given field is translatable
+ * a (not necessarily strict) subset of the current enabled languages will be returned,
+ * otherwise only FIELD_LANGUAGE_NONE will be returned. This way, since the default
+ * value for the "translatble" entity property is FALSE, we ensure that only entities
+ * able to handle translations actually get translatable fields.
+ *
+ * @param $obj_type
+ *   The type of the entity the field is attached to; e.g. 'node' or 'user'.
+ * @param $field
+ *   A field structure.
+ * @param $suggested_languages
+ *   An array of language preferences which will be intersected with the enabled languages.
+ * @returns
+ *   An array of valid language codes.
+ */
+function field_multilingual_available_languages($obj_type, $field, $suggested_languages = NULL) {
+  $field_languages = &drupal_static(__FUNCTION__, array());
+  $field_name = $field['field_name'];
+
+  if (!isset($field_languages[$field_name]) || !empty($suggested_languages)) {
+    $obj_info = field_info_fieldable_types($obj_type);
+    if (!empty($obj_info['translation_handlers']) && $field['translatable']) {
+      $available_languages = field_multilingual_content_languages();
+      // The returned languages are a subset of the intersection of enabled ones and suggested ones.
+      $languages = !empty($suggested_languages) ? $available_languages = array_intersect($available_languages, $suggested_languages) : $available_languages;
+      foreach (module_implements('field_languages') as $module) {
+        $function = $module . '_field_languages';
+        $function($obj_type, $field, $languages);
+      }
+      // Accept only available languages.
+      $result = array_values(array_intersect($available_languages, $languages));
+      // Don't cache suggested values as they might alter the general result.
+      if (empty($suggested_languages)) {
+        $field_languages[$field_name] = $result;
+      }
+    }
+    else {
+      $result = $field_languages[$field_name] = array(FIELD_LANGUAGE_NONE);
+    }
+  }
+  else {
+    $result = $field_languages[$field_name];
+  }
+
+  return $result;
+}
+
+/**
+ * Return the available content languages. 
+ *
+ * The languages that may be associated to fields include FIELD_LANGAUGE_NONE.
+ *
+ * @return 
+ *   An array of language codes.
+ */
+function field_multilingual_content_languages() {
+  return array_keys(language_list() + array(FIELD_LANGUAGE_NONE => NULL));
+}
+
+
+/**
+ * Check if a module is registered a s a translation handler for a given entity.
+ *
+ * @param $obj_type
+ *   The type of the entity whose fields are to be translated. 
+ * @param $handler
+ *   The name of the handler which has to be checked.
+ * @return
+ *   A boolean indicating if the handler is allowed to manage field translations.
+ */
+function field_multilingual_check_translation_handler($obj_type, $handler) {
+  $obj_info = field_info_fieldable_types($obj_type);
+  return isset($obj_info['translation_handlers'][$handler]);
+}
+
+/**
+ * Helper function which ensures the the given language code is valid.
+ * 
+ * Check if the given language is one of the enabled languages, otherwise 
+ * depnding on the $default variable's value return the default language code
+ * or the current language one.
+ * 
+ * @params $language
+ *   The language code to be checked.
+ * @params $default
+ *   Whether return the default language code or the current one.
+ * @returns
+ *   A valid language code.
+ */
+function field_multilingual_valid_language($language, $default = TRUE) {
+  $enabled_languages = field_multilingual_content_languages();
+  if (in_array($language, $enabled_languages)) {
+    return $language;
+  }
+  // Currently node language neutral code is an empty string.
+  // TODO: we might want to unify the language codes. 
+  if ($language === '') {
+    return FIELD_LANGUAGE_NONE;
+  }
+  global $language;
+  $valid_language = $default ? language_default('language') : $language->language;
+  if (in_array($valid_language, $enabled_languages)) {
+    return $valid_language;
+  }
+  // TODO: throw a more specific exception
+  throw new FieldException('No valid content language could be found');
+}