diff --git a/core/lib/Drupal/Core/Config/Config.php b/core/lib/Drupal/Core/Config/Config.php
index bdeeba1..b3b51c2 100644
--- a/core/lib/Drupal/Core/Config/Config.php
+++ b/core/lib/Drupal/Core/Config/Config.php
@@ -110,7 +110,7 @@ public function get($key = '') {
    * {@inheritdoc}
    */
   public function setData(array $data) {
-    $this->data = $data;
+    parent::setData($data);
     $this->resetOverriddenData();
     return $this;
   }
diff --git a/core/lib/Drupal/Core/Config/ConfigBase.php b/core/lib/Drupal/Core/Config/ConfigBase.php
index 3508611..37e0d80 100644
--- a/core/lib/Drupal/Core/Config/ConfigBase.php
+++ b/core/lib/Drupal/Core/Config/ConfigBase.php
@@ -160,13 +160,39 @@ public function get($key = '') {
    *
    * @return $this
    *   The configuration object.
+   *
+   * @throws \Drupal\Core\Config\ConfigValueException
+   *   If any key in $data in any depth contains a dot.
    */
   public function setData(array $data) {
+    $this->validateKeys($data);
     $this->data = $data;
     return $this;
   }
 
   /**
+   * Validate all keys in a passed in config array structure.
+   *
+   * @param array $data
+   *   Configuration array structure.
+   *
+   * @return null
+   *
+   * @throws \Drupal\Core\Config\ConfigValueException
+   *   If any key in $data in any depth contains a dot.
+   */
+  protected function validateKeys(array $data) {
+    foreach ($data as $key => $value) {
+      if (strpos($key, '.') !== FALSE) {
+        throw new ConfigValueException(String::format('@key key contains a dot which is not supported.', array('@key' => $key)));
+      }
+      if (is_array($value)) {
+        $this->validateKeys($value);
+      }
+    }
+  }
+
+  /**
    * Sets a value in this configuration object.
    *
    * @param string $key
@@ -176,10 +202,16 @@ public function setData(array $data) {
    *
    * @return $this
    *   The configuration object.
+   *
+   * @throws \Drupal\Core\Config\ConfigValueException
+   *   If $value is an array and any of its keys in any depth contains a dot.
    */
   public function set($key, $value) {
     // The dot/period is a reserved character; it may appear between keys, but
     // not within keys.
+    if (is_array($value)) {
+      $this->validateKeys($value);
+    }
     $parts = explode('.', $key);
     if (count($parts) == 1) {
       $this->data[$key] = $value;
diff --git a/core/lib/Drupal/Core/Config/ConfigValueException.php b/core/lib/Drupal/Core/Config/ConfigValueException.php
new file mode 100644
index 0000000..9802228
--- /dev/null
+++ b/core/lib/Drupal/Core/Config/ConfigValueException.php
@@ -0,0 +1,13 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Config\ConfigValueException.
+ */
+
+namespace Drupal\Core\Config;
+
+/**
+ * Exception thrown when config object values are invalid.
+ */
+class ConfigValueException extends ConfigException {}
diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
index d014890..28fc178 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
@@ -166,7 +166,7 @@ protected function doLoadMultiple(array $ids = NULL) {
     // Load all of the configuration entities.
     $records = array();
     foreach ($this->configFactory->loadMultiple($names) as $config) {
-      $records[$config->get($this->idKey)] = $config->get();
+      $records[$config->get($this->idKey)] = $this->postLoadData($config->get());
     }
     return $this->mapFromStorageRecords($records);
   }
@@ -237,7 +237,7 @@ protected function doSave($id, EntityInterface $entity) {
     }
 
     // Retrieve the desired properties and set them in config.
-    foreach ($entity->toArray() as $key => $value) {
+    foreach ($this->preSaveData($entity->toArray(), $entity) as $key => $value) {
       $config->set($key, $value);
     }
     $config->save();
@@ -246,6 +246,32 @@ protected function doSave($id, EntityInterface $entity) {
   }
 
   /**
+   * Alter data for the storage environment right before saving.
+   *
+   * @param array $data
+   *   Raw configuration data being saved.
+   *
+   * @return array
+   *   Data to save with any modifications necessary for storage performed.
+   */
+  protected function preSaveData(array $data) {
+    return $data;
+  }
+
+  /**
+   * Alter data from the storage environment right after loading.
+   *
+   * @param array $data
+   *   Raw configuration data as loaded.
+   *
+   * @return array
+   *   Transformed data with any modifications necessary for instantiation.
+   */
+  protected function postLoadData(array $data) {
+    return $data;
+  }
+
+  /**
    * {@inheritdoc}
    */
   protected function has($id, EntityInterface $entity) {
diff --git a/core/lib/Drupal/Core/Field/FieldItemBase.php b/core/lib/Drupal/Core/Field/FieldItemBase.php
index 296c468..f168001 100644
--- a/core/lib/Drupal/Core/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Field/FieldItemBase.php
@@ -255,4 +255,24 @@ public function instanceSettingsForm(array $form, array &$form_state) {
     return array();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function preSaveSettings(array &$settings) { }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function postLoadSettings(array &$settings) { }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function preSaveInstanceSettings(array &$settings) { }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function postLoadInstanceSettings(array &$settings) { }
+
 }
diff --git a/core/lib/Drupal/Core/Field/FieldItemInterface.php b/core/lib/Drupal/Core/Field/FieldItemInterface.php
index ee27996..8b624c7 100644
--- a/core/lib/Drupal/Core/Field/FieldItemInterface.php
+++ b/core/lib/Drupal/Core/Field/FieldItemInterface.php
@@ -183,6 +183,48 @@ public function view($display_options = array());
   public function preSave();
 
   /**
+   * Defines behavior for transforming field settings before being saved.
+   *
+   * May be used to alter settings to transform them to a storage-friendly form.
+   *
+   * @param array $settings
+   *   Field settings.
+   */
+  public static function preSaveSettings(array &$settings);
+
+  /**
+   * Defines custom behavior for transforming field settings when loading.
+   *
+   * May be used to alter settings to transform them from a storage-friendly
+   * form.
+   *
+   * @param array $settings
+   *   Field settings.
+   */
+  public static function postLoadSettings(array &$settings);
+
+  /**
+   * Defines behavior for transforming instance settings before being saved.
+   *
+   * May be used to alter settings to transform them to a storage-friendly form.
+   *
+   * @param array $settings
+   *   Field settings.
+   */
+  public static function preSaveInstanceSettings(array &$settings);
+
+  /**
+   * Defines custom behavior for transforming instance settings when loading.
+   *
+   * May be used to alter settings to transform them from a storage-friendly
+   * form.
+   *
+   * @param array $settings
+   *   Field settings.
+   */
+  public static function postLoadInstanceSettings(array &$settings);
+
+  /**
    * Defines custom insert behavior for field values.
    *
    * This method is called during the process of inserting an entity, just
diff --git a/core/modules/config/src/Tests/ConfigCRUDTest.php b/core/modules/config/src/Tests/ConfigCRUDTest.php
index 122843e..c38d3f6 100644
--- a/core/modules/config/src/Tests/ConfigCRUDTest.php
+++ b/core/modules/config/src/Tests/ConfigCRUDTest.php
@@ -9,6 +9,7 @@
 
 use Drupal\Component\Utility\String;
 use Drupal\Core\Config\ConfigNameException;
+use Drupal\Core\Config\ConfigValueException;
 use Drupal\Core\Config\InstallStorage;
 use Drupal\simpletest\DrupalUnitTestBase;
 use Drupal\Core\Config\FileStorage;
@@ -184,6 +185,31 @@ function testNameValidation() {
   }
 
   /**
+   * Tests the validation of configuration object values.
+   */
+  function testValueValidation() {
+    // Verify that setData() will catch dotted keys.
+    $message = 'Expected ConfigValueException was thrown from setData() for value with dotted keys.';
+    try {
+      \Drupal::config('namespace.object')->setData(array('key.value' => 12))->save();
+      $this->fail($message);
+    }
+    catch (ConfigValueException $e) {
+      $this->pass($message);
+    }
+
+    // Verify that set() will catch dotted keys.
+    $message = 'Expected ConfigValueException was thrown from set() for value with dotted keys.';
+    try {
+      \Drupal::config('namespace.object')->set('foo', array('key.value' => 12))->save();
+      $this->fail($message);
+    }
+    catch (ConfigValueException $e) {
+      $this->pass($message);
+    }
+  }
+
+  /**
    * Tests data type handling.
    */
   public function testDataTypes() {
diff --git a/core/modules/field/src/Entity/FieldInstanceConfig.php b/core/modules/field/src/Entity/FieldInstanceConfig.php
index 79830db..3a5314d 100644
--- a/core/modules/field/src/Entity/FieldInstanceConfig.php
+++ b/core/modules/field/src/Entity/FieldInstanceConfig.php
@@ -253,7 +253,7 @@ public function __construct(array $values, $entity_type = 'field_instance_config
     }
 
     // Discard the 'field_type' entry that is added in config records to ease
-    // schema generation. See self::toArray().
+    // schema generation and data altering for storage. See self::toArray().
     unset($values['field_type']);
 
     parent::__construct($values, $entity_type);
@@ -287,7 +287,8 @@ public function getType() {
   public function toArray() {
     $properties = parent::toArray();
     // Additionally, include the field type, that is needed to be able to
-    // generate the field-type-dependant parts of the config schema.
+    // generate the field-type-dependant parts of the config schema and to
+    // allow for altering data by field type.
     $properties['field_type'] = $this->getType();
 
     return $properties;
diff --git a/core/modules/field/src/FieldStorageConfigStorage.php b/core/modules/field/src/FieldStorageConfigStorage.php
index 8419424..18216dc 100644
--- a/core/modules/field/src/FieldStorageConfigStorage.php
+++ b/core/modules/field/src/FieldStorageConfigStorage.php
@@ -10,6 +10,7 @@
 
 use Drupal\Component\Uuid\UuidInterface;
 use Drupal\Core\Config\Entity\ConfigEntityStorage;
+use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\Language\LanguageManagerInterface;
@@ -156,4 +157,27 @@ public function loadByProperties(array $conditions = array()) {
     return $matches;
 
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function postLoadData(array $data) {
+    // @todo Makes too much assumptions but it needs to.
+    $type_definition = \Drupal::typedDataManager()
+      ->getDefinition('field_item:' . $data['type']);
+    $type_definition['class']::postLoadSettings($data['settings']);
+    return $data;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function preSaveData(array $data) {
+    // @todo Makes too much assumptions but it needs to.
+    $type_definition = \Drupal::typedDataManager()
+      ->getDefinition('field_item:' . $data['type']);
+    $type_definition['class']::preSaveSettings($data['settings']);
+    return $data;
+  }
+
 }
diff --git a/core/modules/field/src/FieldInstanceConfigStorage.php b/core/modules/field/src/FieldInstanceConfigStorage.php
index 20dc083..26dc9f4 100644
--- a/core/modules/field/src/FieldInstanceConfigStorage.php
+++ b/core/modules/field/src/FieldInstanceConfigStorage.php
@@ -177,4 +177,25 @@ public function loadByProperties(array $conditions = array()) {
     return $matching_instances;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function postLoadData(array $data) {
+    // @todo Makes too much assumptions but it needs to.
+    $type_definition = \Drupal::typedDataManager()
+      ->getDefinition('field_item:' . $data['field_type']);
+    $type_definition['class']::postLoadInstanceSettings($data['settings']);
+    return $data;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function preSaveData(array $data) {
+    // @todo Makes too much assumptions but it needs to.
+    $type_definition = \Drupal::typedDataManager()
+      ->getDefinition('field_item:' . $data['field_type']);
+    $type_definition['class']::preSaveInstanceSettings($data['settings']);
+    return $data;
+  }
 }
diff --git a/core/modules/options/config/schema/options.schema.yml b/core/modules/options/config/schema/options.schema.yml
index 39ed439..7a639cb 100644
--- a/core/modules/options/config/schema/options.schema.yml
+++ b/core/modules/options/config/schema/options.schema.yml
@@ -8,8 +8,15 @@ field.list_integer.settings:
       type: sequence
       label: 'Allowed values list'
       sequence:
-        - type: string
-          label: 'Value'
+        - type: mapping
+          label: 'Allowed value with label'
+          mapping:
+            value:
+              type: integer
+              label: 'Value'
+            label:
+              type: label
+              label: 'Label'
     allowed_values_function:
       type: string
       label: 'Allowed values function'
@@ -35,8 +42,18 @@ field.list_float.settings:
   label: 'List (float) settings'
   mapping:
     allowed_values:
-      type: ignore
+      type: sequence
       label: 'Allowed values list'
+      sequence:
+        - type: mapping
+          label: 'Allowed value with label'
+          mapping:
+            value:
+              type: float
+              label: 'Value'
+            label:
+              type: label
+              label: 'Label'
     allowed_values_function:
       type: string
       label: 'Allowed values function'
@@ -65,8 +82,15 @@ field.list_text.settings:
       type: sequence
       label: 'Allowed values list'
       sequence:
-        - type: string
-          label: 'Value'
+        - type: mapping
+          label: 'Allowed value with label'
+          mapping:
+            value:
+              type: string
+              label: 'Value'
+            label:
+              type: label
+              label: 'Label'
     allowed_values_function:
       type: string
       label: 'Allowed values function'
diff --git a/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php b/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php
index 30cd382..1b2d323 100644
--- a/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php
+++ b/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php
@@ -90,4 +90,24 @@ protected static function validateAllowedValue($option) {
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function simplifyAllowedValues(array $structured_values) {
+    $values = array();
+    foreach ($structured_values as $item) {
+      // Nested elements are embedded in the label.
+      // See ListItemBase::structureAllowedValues().
+      if (is_array($item['label'])) {
+        $item['label'] = static::simplifyAllowedValues($item['label']);
+      }
+      // Cast the value to a float first so that .5 and 0.5 are the same value
+      // and then cast to a string so that values like 0.5 can be used as array
+      // keys.
+      // @see http://php.net/manual/en/language.types.array.php
+      $values[(string) (float) $item['value']] = $item['label'];
+    }
+    return $values;
+  }
+
 }
diff --git a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
index d61aef1..f63b17f 100644
--- a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
+++ b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
@@ -237,4 +237,71 @@ protected function allowedValuesString($values) {
     return implode("\n", $lines);
   }
 
+  /**
+   * Defined in \Drupal\Core\Field\FieldItemInterface.
+   */
+  public static function preSaveSettings(array &$settings) {
+    if (isset($settings['allowed_values'])) {
+      $settings['allowed_values'] = static::structureAllowedValues($settings['allowed_values']);
+    }
+  }
+
+  /**
+   * Defined in \Drupal\Core\Field\FieldItemInterface.
+   */
+  public static function postLoadSettings(array &$settings) {
+    if (isset($settings['allowed_values'])) {
+      $settings['allowed_values'] = static::simplifyAllowedValues($settings['allowed_values']);
+    }
+  }
+
+  /**
+   * Simplify allowed values to a key-value array from the structured array.
+   *
+   * @param array $structured_values
+   *   Array of items with a 'value' and 'label' key each for the allowed
+   *   values.
+   *
+   * @return array
+   *   Allowed values were the array key is the 'value' value, the value is
+   *   the 'label' value.
+   */
+  protected static function simplifyAllowedValues(array $structured_values) {
+    $values = array();
+    foreach ($structured_values as $item) {
+      if (is_array($item['label'])) {
+        // Nested elements are embedded in the label.
+        // See structureAllowedValues().
+        $item['label'] = static::simplifyAllowedValues($item['label']);
+      }
+      $values[$item['value']] = $item['label'];
+    }
+    return $values;
+  }
+
+  /**
+   * Creates a structured array of allowed values from a key-value array.
+   *
+   * @param array $values
+   *   Allowed values were the array key is the 'value' value, the value is
+   *   the 'label' value.
+   *
+   * @return array
+   *   Array of items with a 'value' and 'label' key each for the allowed
+   *   values.
+   */
+  protected static function structureAllowedValues(array $values) {
+    $structured_values = array();
+    foreach ($values as $value => $label) {
+      if (is_array($label)) {
+        $label = static::structureAllowedValues($label);
+      }
+      $structured_values[] = array(
+        'value' => $value,
+        'label' => $label,
+      );
+    }
+    return $structured_values;
+  }
+
 }
diff --git a/core/modules/options/src/Tests/OptionsFieldUITest.php b/core/modules/options/src/Tests/OptionsFieldUITest.php
index c69e797..0eac490 100644
--- a/core/modules/options/src/Tests/OptionsFieldUITest.php
+++ b/core/modules/options/src/Tests/OptionsFieldUITest.php
@@ -94,6 +94,11 @@ function testOptionsAllowedValuesInteger() {
     $string = "0|Zero";
     $array = array('0' => 'Zero');
     $this->assertAllowedValuesInput($string, $array, 'Values not in use can be removed.');
+
+    // Check that the same key can only be used once.
+    $string = "0|Zero\n0|One";
+    $array = array('0' => 'One');
+    $this->assertAllowedValuesInput($string, $array, 'Same value cannot be used multiple times.');
   }
 
   /**
@@ -144,6 +149,16 @@ function testOptionsAllowedValuesFloat() {
     $string = "0|Zero";
     $array = array('0' => 'Zero');
     $this->assertAllowedValuesInput($string, $array, 'Values not in use can be removed.');
+
+    // Check that the same key can only be used once.
+    $string = "0.5|Point five\n0.5|Half";
+    $array = array('0.5' => 'Half');
+    $this->assertAllowedValuesInput($string, $array, 'Same value cannot be used multiple times.');
+
+    // Check that different forms of the same float value cannot be used.
+    $string = "0|Zero\n.5|Point five\n0.5|Half";
+    $array = array('0' => 'Zero', '0.5' => 'Half');
+    $this->assertAllowedValuesInput($string, $array, 'Different forms of the same value cannot be used.');
   }
 
   /**
@@ -199,6 +214,16 @@ function testOptionsAllowedValuesText() {
     $string = "Zero";
     $array = array('Zero' => 'Zero');
     $this->assertAllowedValuesInput($string, $array, 'Values not in use can be removed.');
+
+    // Check that string values with dots can be used.
+    $string = "Zero\nexample.com|Example";
+    $array = array('Zero' => 'Zero', 'example.com' => 'Example');
+    $this->assertAllowedValuesInput($string, $array, 'String value with dot is supported.');
+
+    // Check that the same key can only be used once.
+    $string = "zero|Zero\nzero|One";
+    $array = array('zero' => 'One');
+    $this->assertAllowedValuesInput($string, $array, 'Same value cannot be used multiple times.');
   }
 
   /**