Index: includes/bootstrap.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/bootstrap.inc,v
retrieving revision 1.330
diff -u -p -r1.330 bootstrap.inc
--- includes/bootstrap.inc	22 Nov 2009 08:20:51 -0000	1.330
+++ includes/bootstrap.inc	2 Dec 2009 16:36:25 -0000
@@ -179,6 +179,13 @@ define('DRUPAL_AUTHENTICATED_RID', 2);
 define('DRUPAL_KILOBYTE', 1024);
 
 /**
+ * The language code used when no language is explicitly assigned.
+ *
+ * Defined by ISO639-2 for "No linguistic content / Not applicable".
+ */
+define('FIELD_LANGUAGE_NONE', 'zxx');
+
+/**
  * The type of language used to define the content language.
  */
 define('LANGUAGE_TYPE_CONTENT', 'language');
Index: includes/path.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/path.inc,v
retrieving revision 1.50
diff -u -p -r1.50 path.inc
--- includes/path.inc	2 Dec 2009 07:28:22 -0000	1.50
+++ includes/path.inc	2 Dec 2009 16:36:25 -0000
@@ -43,7 +43,7 @@ function drupal_path_initialize() {
  *   Either a Drupal system path, an aliased path, or FALSE if no path was
  *   found.
  */
-function drupal_lookup_path($action, $path = '', $path_language = '') {
+function drupal_lookup_path($action, $path = '', $path_language = NULL) {
   global $language;
   // Use the advanced drupal_static() pattern, since this is called very often.
   static $drupal_static = array();
@@ -90,9 +90,10 @@ function drupal_lookup_path($action, $pa
           // Now fetch the aliases corresponding to these system paths.
           // We order by ASC and overwrite array keys to ensure the correct
           // alias is used when there are multiple aliases per path.
-          $cache['map'][$path_language] = db_query("SELECT source, alias FROM {url_alias} WHERE source IN (:system) AND language IN (:language, '') ORDER BY language ASC, pid ASC", array(
+          $cache['map'][$path_language] = db_query("SELECT source, alias FROM {url_alias} WHERE source IN (:system) AND language IN (:language, :language_none) ORDER BY language ASC, pid ASC", array(
             ':system' => $cache['system_paths'],
-            ':language' => $path_language
+            ':language' => $path_language,
+            ':language_none' => FIELD_LANGUAGE_NONE,
           ))->fetchAllKeyed();
           // Keep a record of paths with no alias to avoid querying twice.
           $cache['no_aliases'][$path_language] = array_flip(array_diff_key($cache['system_paths'], array_keys($cache['map'][$path_language])));
@@ -111,9 +112,10 @@ function drupal_lookup_path($action, $pa
       // For system paths which were not cached, query aliases individually.
       else if (!isset($cache['no_aliases'][$path_language][$path])) {
         // Get the most fitting result falling back with alias without language
-        $alias = db_query("SELECT alias FROM {url_alias} WHERE source = :source AND language IN (:language, '') ORDER BY language DESC, pid DESC", array(
+        $alias = db_query("SELECT alias FROM {url_alias} WHERE source = :source AND language IN (:language, :language_none) ORDER BY language DESC, pid DESC", array(
           ':source' => $path,
-          ':language' => $path_language
+          ':language' => $path_language,
+          ':language_none' => FIELD_LANGUAGE_NONE,
         ))->fetchField();
         $cache['map'][$path_language][$path] = $alias;
         return $alias;
@@ -126,9 +128,10 @@ function drupal_lookup_path($action, $pa
       $source = '';
       if (!isset($cache['map'][$path_language]) || !($source = array_search($path, $cache['map'][$path_language]))) {
         // Get the most fitting result falling back with alias without language
-        if ($source = db_query("SELECT source FROM {url_alias} WHERE alias = :alias AND language IN (:language, '') ORDER BY language DESC, pid DESC", array(
+        if ($source = db_query("SELECT source FROM {url_alias} WHERE alias = :alias AND language IN (:language, :language_none) ORDER BY language DESC, pid DESC", array(
                      ':alias' => $path,
-                     ':language' => $path_language))
+                     ':language' => $path_language,
+                     ':language_none' => FIELD_LANGUAGE_NONE))
             ->fetchField()) {
           $cache['map'][$path_language][$source] = $path;
         }
@@ -186,7 +189,7 @@ function drupal_cache_system_paths() {
  *   An aliased path if one was found, or the original path if no alias was
  *   found.
  */
-function drupal_get_path_alias($path = NULL, $path_language = '') {
+function drupal_get_path_alias($path = NULL, $path_language = NULL) {
   // If no path is specified, use the current page's path.
   if ($path == NULL) {
     $path = $_GET['q'];
@@ -210,7 +213,7 @@ function drupal_get_path_alias($path = N
  *   The internal path represented by the alias, or the original alias if no
  *   internal path was found.
  */
-function drupal_get_normal_path($path, $path_language = '') {
+function drupal_get_normal_path($path, $path_language = NULL) {
   $original_path = $path;
 
   // Lookup the path alias first.
@@ -445,7 +448,7 @@ function path_load($conditions) {
  *   - language: (optional) The language of the alias.
  */
 function path_save(&$path) {
-  $path += array('pid' => NULL, 'language' => '');
+  $path += array('pid' => NULL, 'language' => FIELD_LANGUAGE_NONE);
 
   // Insert or update the alias.
   $status = drupal_write_record('url_alias', $path, (!empty($path['pid']) ? 'pid' : NULL));
Index: modules/comment/comment.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/comment/comment.module,v
retrieving revision 1.812
diff -u -p -r1.812 comment.module
--- modules/comment/comment.module	1 Dec 2009 16:03:35 -0000	1.812
+++ modules/comment/comment.module	2 Dec 2009 16:36:25 -0000
@@ -1672,7 +1672,7 @@ function comment_form($form, &$form_stat
     'comment' => '',
     'cid' => NULL,
     'pid' => NULL,
-    'language' => '',
+    'language' => FIELD_LANGUAGE_NONE,
     'uid' => 0,
   );
   $comment = (object) $comment;
Index: modules/field/field.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.module,v
retrieving revision 1.49
diff -u -p -r1.49 field.module
--- modules/field/field.module	2 Dec 2009 08:08:11 -0000	1.49
+++ modules/field/field.module	2 Dec 2009 16:36:25 -0000
@@ -70,13 +70,6 @@ module_load_include('inc', 'field', 'fie
 define('FIELD_CARDINALITY_UNLIMITED', -1);
 
 /**
- * The language code assigned to untranslatable fields.
- *
- * Defined by ISO639-2 for "No linguistic content / Not applicable".
- */
-define('FIELD_LANGUAGE_NONE', 'zxx');
-
-/**
  * TODO
  */
 define('FIELD_BEHAVIOR_NONE', 0x0001);
Index: modules/field/field.multilingual.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/field/field.multilingual.inc,v
retrieving revision 1.4
diff -u -p -r1.4 field.multilingual.inc
--- modules/field/field.multilingual.inc	31 Oct 2009 16:06:35 -0000	1.4
+++ modules/field/field.multilingual.inc	2 Dec 2009 16:36:25 -0000
@@ -71,7 +71,7 @@ function field_multilingual_available_la
 /**
  * Return available content languages.
  *
- * The languages that may be associated to fields include FIELD_LANGAUGE_NONE.
+ * The languages that may be associated to fields include FIELD_LANGUAGE_NONE.
  *
  * @return
  *   An array of language codes.
@@ -132,12 +132,6 @@ function field_multilingual_valid_langua
   if (in_array($langcode, $enabled_languages)) {
     return $langcode;
   }
-  // @todo Currently, node language neutral code is an empty string. Node passes
-  //   $node->language as language parameter to field_attach_form(). We might
-  //   want to unify the two "language neutral" language codes.
-  if ($langcode === '') {
-    return FIELD_LANGUAGE_NONE;
-  }
   global $language;
   $langcode = $default ? language_default('language') : $language->language;
   if (in_array($langcode, $enabled_languages)) {
Index: modules/locale/locale.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/locale/locale.module,v
retrieving revision 1.272
diff -u -p -r1.272 locale.module
--- modules/locale/locale.module	2 Dec 2009 00:28:43 -0000	1.272
+++ modules/locale/locale.module	2 Dec 2009 16:36:25 -0000
@@ -412,7 +412,7 @@ function locale_form_alter(&$form, &$for
         '#type' => 'select',
         '#title' => t('Language'),
         '#default_value' => (isset($form['#node']->language) ? $form['#node']->language : ''),
-        '#options' => array('' => t('Language neutral')) + locale_language_list('name'),
+        '#options' => array(FIELD_LANGUAGE_NONE => t('Language neutral')) + locale_language_list('name'),
       );
     }
     // Node type without language selector: assign the default for new nodes
Index: modules/node/node.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.admin.inc,v
retrieving revision 1.79
diff -u -p -r1.79 node.admin.inc
--- modules/node/node.admin.inc	2 Dec 2009 14:56:32 -0000	1.79
+++ modules/node/node.admin.inc	2 Dec 2009 16:36:25 -0000
@@ -108,7 +108,7 @@ function node_filters() {
   }
   // Language filter if there is a list of languages
   if ($languages = module_invoke('locale', 'language_list')) {
-    $languages = array('' => t('Language neutral')) + $languages;
+    $languages = array(FIELD_LANGUAGE_NONE => t('Language neutral')) + $languages;
     $filters['language'] = array(
       'title' => t('language'),
       'options' => array(
@@ -169,7 +169,7 @@ function node_filter_form() {
       $value = $value->name;
     }
     elseif ($type == 'language') {
-      $value = empty($value) ? t('Language neutral') : module_invoke('locale', 'language_name', $value);
+      $value = $value == FIELD_LANGUAGE_NONE ? t('Language neutral') : module_invoke('locale', 'language_name', $value);
     }
     else {
       $value = $filters[$type]['options'][$value];
@@ -436,7 +436,7 @@ function node_admin_nodes() {
 
   // Enable language column if translation module is enabled
   // or if we have any node with language.
-  $multilanguage = (module_exists('translation') || db_query("SELECT COUNT(*) FROM {node} WHERE language <> ''")->fetchField());
+  $multilanguage = (module_exists('translation') || db_query("SELECT COUNT(*) FROM {node} WHERE language <> :language", array(':language' => FIELD_LANGUAGE_NONE))->fetchField());
 
   // Build the sortable table header.
   $header = array(
@@ -482,7 +482,7 @@ function node_admin_nodes() {
   $destination = drupal_get_destination();
   $options = array();
   foreach ($nodes as $node) {
-    $l_options = !empty($node->language) ? array('language' => $languages[$node->language]) : array();
+    $l_options = $node->language != FIELD_LANGUAGE_NONE ? array('language' => $languages[$node->language]) : array();
     $options[$node->nid] = array(
       'title' => array(
         'data' => array(
@@ -499,7 +499,7 @@ function node_admin_nodes() {
       'changed' => format_date($node->changed, 'short'),
     );
     if ($multilanguage) {
-      $options[$node->nid]['language'] = empty($node->language) ? t('Language neutral') : t($languages[$node->language]->name);
+      $options[$node->nid]['language'] = $node->language == FIELD_LANGUAGE_NONE ? t('Language neutral') : t($languages[$node->language]->name);
     }
     // Build a list of all the accessible operations for the current node.
     $operations = array();
Index: modules/node/node.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.install,v
retrieving revision 1.35
diff -u -p -r1.35 node.install
--- modules/node/node.install	14 Nov 2009 07:58:49 -0000	1.35
+++ modules/node/node.install	2 Dec 2009 16:36:25 -0000
@@ -566,6 +566,16 @@ function node_update_7008() {
 }
 
 /**
+ * Convert node languages from the empty string to FIELD_LANGUAGE_NONE.
+ */
+function node_update_7009() {
+  db_update('node')
+    ->fields(array('language' => FIELD_LANGUAGE_NONE))
+    ->condition('language', '')
+    ->execute();
+}
+
+/**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
  */
Index: modules/node/node.pages.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/node/node.pages.inc,v
retrieving revision 1.102
diff -u -p -r1.102 node.pages.inc
--- modules/node/node.pages.inc	1 Dec 2009 16:03:35 -0000	1.102
+++ modules/node/node.pages.inc	2 Dec 2009 16:36:25 -0000
@@ -62,7 +62,7 @@ function node_add($type) {
   // If a node type has been specified, validate its existence.
   if (isset($types[$type])) {
     // Initialize settings:
-    $node = (object)array('uid' => $user->uid, 'name' => (isset($user->name) ? $user->name : ''), 'type' => $type, 'language' => '');
+    $node = (object)array('uid' => $user->uid, 'name' => (isset($user->name) ? $user->name : ''), 'type' => $type, 'language' => FIELD_LANGUAGE_NONE);
 
     drupal_set_title(t('Create @name', array('@name' => $types[$type]->name)), PASS_THROUGH);
     $output = drupal_get_form($type . '_node_form', $node);
Index: modules/path/path.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/path/path.admin.inc,v
retrieving revision 1.37
diff -u -p -r1.37 path.admin.inc
--- modules/path/path.admin.inc	2 Dec 2009 14:56:32 -0000	1.37
+++ modules/path/path.admin.inc	2 Dec 2009 16:36:25 -0000
@@ -16,7 +16,7 @@ function path_admin_overview($keys = NUL
   // Add the filter form above the overview table.
   $build['path_admin_filter_form'] = drupal_get_form('path_admin_filter_form', $keys);
   // Enable language column if locale is enabled or if we have any alias with language
-  $alias_exists = (bool) db_query_range('SELECT 1 FROM {url_alias} WHERE language <> :language', 0, 1, array(':language' => ''))->fetchField();
+  $alias_exists = (bool) db_query_range('SELECT 1 FROM {url_alias} WHERE language <> :language', 0, 1, array(':language' => FIELD_LANGUAGE_NONE))->fetchField();
   $multilanguage = (module_exists('locale') || $alias_exists);
 
   $header = array(
@@ -94,7 +94,7 @@ function path_admin_edit($path = array()
  * @see path_admin_form_validate()
  * @see path_admin_form_submit()
  */
-function path_admin_form($form, &$form_state, $path = array('source' => '', 'alias' => '', 'language' => '', 'pid' => NULL)) {
+function path_admin_form($form, &$form_state, $path = array('source' => '', 'alias' => '', 'language' => FIELD_LANGUAGE_NONE, 'pid' => NULL)) {
   $form['source'] = array(
     '#type' => 'textfield',
     '#title' => t('Existing system path'),
@@ -151,7 +151,7 @@ function path_admin_form_validate($form,
   $alias = $form_state['values']['alias'];
   $pid = isset($form_state['values']['pid']) ? $form_state['values']['pid'] : 0;
   // Language is only set if locale module is enabled, otherwise save for all languages.
-  $language = isset($form_state['values']['language']) ? $form_state['values']['language'] : '';
+  $language = isset($form_state['values']['language']) ? $form_state['values']['language'] : FIELD_LANGUAGE_NONE;
 
   $has_alias = db_query("SELECT COUNT(alias) FROM {url_alias} WHERE pid <> :pid AND alias = :alias AND language = :language", array(
       ':pid' => $pid,
Index: modules/path/path.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/path/path.module,v
retrieving revision 1.177
diff -u -p -r1.177 path.module
--- modules/path/path.module	1 Dec 2009 13:14:42 -0000	1.177
+++ modules/path/path.module	2 Dec 2009 16:36:25 -0000
@@ -100,7 +100,7 @@ function path_form_alter(&$form, $form_s
     $path = array();
     if (!empty($form['#node']->nid)) {
       $conditions = array('source' => 'node/' . $form['#node']->nid);
-      if (!empty($form['#node']->language)) {
+      if ($form['#node']->language != FIELD_LANGUAGE_NONE) {
         $conditions['language'] = $form['#node']->language;
       }
       $path = path_load($conditions);
@@ -112,7 +112,7 @@ function path_form_alter(&$form, $form_s
       'pid' => NULL,
       'source' => isset($form['#node']->nid) ? 'node/' . $form['#node']->nid : NULL,
       'alias' => '',
-      'language' => isset($form['#node']->language) ? $form['#node']->language : '',
+      'language' => isset($form['#node']->language) ? $form['#node']->language : FIELD_LANGUAGE_NONE,
     );
 
     $form['path'] = array(
@@ -190,7 +190,7 @@ function path_node_insert($node) {
     if (!empty($path['alias'])) {
       // Ensure fields for programmatic executions.
       $path['source'] = 'node/' . $node->nid;
-      $path['language'] = isset($node->language) ? $node->language : '';
+      $path['language'] = isset($node->language) ? $node->language : FIELD_LANGUAGE_NONE;
       path_save($path);
     }
   }
@@ -211,7 +211,7 @@ function path_node_update($node) {
     if (!empty($path['alias'])) {
       // Ensure fields for programmatic executions.
       $path['source'] = 'node/' . $node->nid;
-      $path['language'] = isset($node->language) ? $node->language : '';
+      $path['language'] = isset($node->language) ? $node->language : FIELD_LANGUAGE_NONE;
       path_save($path);
     }
   }
@@ -239,7 +239,7 @@ function path_form_taxonomy_form_term_al
       'pid' => NULL,
       'source' => isset($form['#term']['tid']) ? 'taxonomy/term/' . $form['#term']['tid'] : NULL,
       'alias' => '',
-      'language' => '',
+      'language' => FIELD_LANGUAGE_NONE,
     );
     $form['identification']['path'] = array(
       '#access' => user_access('create url aliases') || user_access('administer url aliases'),
@@ -271,7 +271,7 @@ function path_taxonomy_term_insert($term
     if (!empty($path['alias'])) {
       // Ensure fields for programmatic executions.
       $path['source'] = 'taxonomy/term/' . $term->tid;
-      $path['language'] = '';
+      $path['language'] = FIELD_LANGUAGE_NONE;
       path_save($path);
     }
   }
@@ -292,7 +292,7 @@ function path_taxonomy_term_update($term
     if (!empty($path['alias'])) {
       // Ensure fields for programmatic executions.
       $path['source'] = 'taxonomy/term/' . $term->tid;
-      $path['language'] = '';
+      $path['language'] = FIELD_LANGUAGE_NONE;
       path_save($path);
     }
   }
Index: modules/simpletest/drupal_web_test_case.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/simpletest/drupal_web_test_case.php,v
retrieving revision 1.175
diff -u -p -r1.175 drupal_web_test_case.php
--- modules/simpletest/drupal_web_test_case.php	22 Nov 2009 08:09:21 -0000	1.175
+++ modules/simpletest/drupal_web_test_case.php	2 Dec 2009 16:36:25 -0000
@@ -709,6 +709,7 @@ class DrupalWebTestCase extends DrupalTe
       'type'      => 'page',
       'revisions' => NULL,
       'taxonomy'  => NULL,
+      'language'  => FIELD_LANGUAGE_NONE,
     );
 
     // Use the original node's created time for existing nodes.
@@ -733,8 +734,7 @@ class DrupalWebTestCase extends DrupalTe
       'value' => $this->randomName(32),
       'format' => filter_default_format(),
     );
-    $langcode = !empty($settings['language']) ? $settings['language'] : FIELD_LANGUAGE_NONE;
-    $settings['body'][$langcode][0] += $body;
+    $settings['body'][$settings['language']][0] += $body;
 
     $node = (object) $settings;
     node_save($node);
Index: modules/system/system.install
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.install,v
retrieving revision 1.426
diff -u -p -r1.426 system.install
--- modules/system/system.install	1 Dec 2009 19:19:49 -0000	1.426
+++ modules/system/system.install	2 Dec 2009 16:36:42 -0000
@@ -2813,6 +2813,16 @@ function system_update_7047() {
 }
 
 /**
+ * Convert path languages from the empty string to FIELD_LANGUAGE_NONE.
+ */
+function system_update_7048() {
+  db_update('url_alias')
+    ->fields(array('language' => FIELD_LANGUAGE_NONE))
+    ->condition('language', '')
+    ->execute();
+}
+
+/**
  * @} End of "defgroup updates-6.x-to-7.x"
  * The next series of updates should start at 8000.
  */
Index: modules/translation/translation.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/translation/translation.module,v
retrieving revision 1.65
diff -u -p -r1.65 translation.module
--- modules/translation/translation.module	1 Dec 2009 13:14:43 -0000	1.65
+++ modules/translation/translation.module	2 Dec 2009 16:36:25 -0000
@@ -76,7 +76,7 @@ function translation_menu() {
  * all languages).
  */
 function _translation_tab_access($node) {
-  if (!empty($node->language) && translation_supported_type($node->type)) {
+  if ($node->language != FIELD_LANGUAGE_NONE && translation_supported_type($node->type)) {
     return user_access('translate content');
   }
   return FALSE;
@@ -122,7 +122,7 @@ function translation_form_alter(&$form, 
       // Disable languages for existing translations, so it is not possible to switch this
       // node to some language which is already in the translation set. Also remove the
       // language neutral option.
-      unset($form['language']['#options']['']);
+      unset($form['language']['#options'][FIELD_LANGUAGE_NONE]);
       foreach (translation_node_get_translations($node->tnid) as $translation) {
         if ($translation->nid != $node->nid) {
           unset($form['language']['#options'][$translation->language]);