diff --git a/README.md b/README.md
index 3dc7987..9a3cf06 100644
--- a/README.md
+++ b/README.md
@@ -22,14 +22,16 @@ greatly appreciated.
 ## Content Types
 
 Below is a list of the (at least partially) implemented content types with
-their fields. *Emphasized fields* were originally planned but proved infeasible
-given the structure of Drupal's RDF module and the Islandora JSON-LD module.
+their fields. The fields with "EDTF L1" accept and display dates corresponding
+to the Library of Congress [2012 Extended Date/Time Format Specification](http://www.loc.gov/standards/datetime/pre-submission.html)
+_Level 1_.  [EDTF was incorporated in ISO 8601-2019 with some modifications](http://www.loc.gov/standards/datetime/edtf.html)
+which will be supported in a future update.
 
 - Corporate Body
   - Preferred Name (Title)
   - Alternate Name
-  - Founding Date (EDTF v.1)
-  - Dissolution Date (EDTF v.1)
+  - Founding Date (EDTF L1)
+  - Dissolution Date (EDTF L1)
   - Parent Organization
   - Authorities
   - Description
@@ -49,14 +51,14 @@ given the structure of Drupal's RDF module and the Islandora JSON-LD module.
   - Display Label (Title)
   - Authorities
   - Relation
-  - Date Begin (EDTF v.1)
-  - Date End (EDTF v.1)
+  - Date Begin (EDTF L1)
+  - Date End (EDTF L1)
 - Person
   - Title/Display Name
   - Alternate Name
   - Preferred Name
-  - Birth Date (EDTF v.1)
-  - Death Date (EDTF v.1)
+  - Birth Date (EDTF L1)
+  - Death Date (EDTF L1)
   - Relation
   - Authorities
   - Description
diff --git a/controlled_access_terms.module b/controlled_access_terms.module
index c31673a..a5fb060 100644
--- a/controlled_access_terms.module
+++ b/controlled_access_terms.module
@@ -7,6 +7,9 @@
 
 use Drupal\jsonld\Normalizer\NormalizerBase;
 use Drupal\Core\Entity\EntityInterface;
+use Drupal\controlled_access_terms\EDTFConverter;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\field\Entity\FieldConfig;
 
 /**
  * Implements hook_rdf_namespaces().
@@ -15,6 +18,7 @@ function controlled_access_terms_rdf_namespaces() {
   return [
     'wgs84_pos' => 'http://www.w3.org/2003/01/geo/wgs84_pos#',
     'org' => 'https://www.w3.org/TR/vocab-org/#org:',
+    'xs' => 'http://www.w3.org/2001/XMLSchema#',
   ];
 }
 
@@ -24,17 +28,113 @@ function controlled_access_terms_rdf_namespaces() {
 function controlled_access_terms_jsonld_alter_normalized_array(EntityInterface $entity, array &$normalized, array $context) {
   if (isset($normalized['@graph']) && is_array($normalized['@graph'])) {
     foreach ($entity->getFieldDefinitions() as $field => $field_definition) {
-      if (($field_definition->getType() == 'typed_relation') && (!empty($entity->get($field)->getValue()))) {
-        foreach ($entity->get($field)->getValue() as $value) {
-          $predicate = NormalizerBase::escapePrefix($value['rel_type'], $context['namespaces']);
-          $referenced_entity = \Drupal::entityTypeManager()->getStorage($field_definition->getSetting('target_type'))->load($value['target_id']);
-          // We are assuming the first graph is the one corresponding
-          // to the node/taxonomy_term we are modifying.
-          $normalized['@graph'][0][$predicate][] = [
-            '@id' => $referenced_entity->toUrl('canonical', ['absolute' => TRUE])->setRouteParameter('_format', 'jsonld')->toString(),
-          ];
+      if (!empty($entity->get($field)->getValue())) {
+        if ($field_definition->getType() == 'typed_relation') {
+          foreach ($entity->get($field)->getValue() as $value) {
+            $predicate = NormalizerBase::escapePrefix($value['rel_type'], $context['namespaces']);
+            $referenced_entity = \Drupal::entityTypeManager()->getStorage($field_definition->getSetting('target_type'))->load($value['target_id']);
+            // We are assuming the first graph is the one corresponding
+            // to the node/taxonomy_term we are modifying.
+            $normalized['@graph'][0][$predicate][] = [
+              '@id' => $referenced_entity->toUrl('canonical', ['absolute' => TRUE])->setRouteParameter('_format', 'jsonld')->toString(),
+            ];
+          }
         }
+        elseif ($field_definition->getType() == 'edtf') {
+          // Get the predicate to look in.
+          foreach ($context['current_entity_rdf_mapping']->get('fieldMappings')[$field]['properties'] as $predicate) {
+            // Find the predicate value that needs updating.
+            $predicate_normalized = NormalizerBase::escapePrefix($predicate, $context['namespaces']);
+            foreach ($normalized['@graph'][0][$predicate_normalized] as $index => $value) {
+              // Clean the date of ranges, uncertainty, and approximations.
+              // Have to remap the array from '@value' to 'value'.
+              $normalized_date = EDTFConverter::dateIso8601Value(['value' => $value['@value']]);
+
+              // Determine which type to use.
+              $date_type = NormalizerBase::escapePrefix('xs:date', $context['namespaces']);
+              switch (count(explode('-', $normalized_date))) {
+                case 1:
+                  $date_type = NormalizerBase::escapePrefix('xs:gYear', $context['namespaces']);
+                  break;
+
+                case 2:
+                  $date_type = NormalizerBase::escapePrefix('xs:gYearMonth', $context['namespaces']);
+                  break;
+              }
+              $normalized['@graph'][0][$predicate_normalized][] = [
+                '@value' => $normalized_date,
+                '@type'  => $date_type,
+              ];
+            }
+          }
+        }
+      }
+    }
+  }
+}
+
+/**
+ * Change fields using the EDTF Widget to the new EDTF Field Type.
+ */
+function controlled_access_terms_update_8002() {
+  // Ensure the new EDTF plugins can be found.
+  \Drupal::service('plugin.manager.field.field_type')->clearCachedDefinitions();
+
+  // Find all the fields using the text_edtf widget via form configs.
+  $config_factory = \Drupal::configFactory();
+  foreach ($config_factory->listAll('core.entity_form_display.') as $entity_form_display_config_name) {
+    $entity_form_display = $config_factory->getEditable($entity_form_display_config_name);
+    $fields = $entity_form_display->get('content');
+    foreach ($fields as $field_name => $field_settings) {
+      if (isset($field_settings['type']) && $field_settings['type'] === 'text_edtf') {
+
+        // Update this form setting.
+        $entity_form_display->set("content.$field_name.type", 'edtf_default');
+
+        // Update the field setting.
+        if (!$fields = \Drupal::entityManager()->getStorage('field_config')->loadByProperties(['field_name' => $field_name])) {
+          continue;
+        }
+        else {
+          foreach ($fields as $field) {
+            $new_field = $field->toArray();
+            $new_field['field_type'] = 'edtf';
+            $new_field = FieldConfig::create($new_field);
+            $new_field->original = $new_field;
+            $new_field->enforceIsNew(FALSE);
+            $new_field->save();
+          }
+        }
+
+        // Update the field storage setting.
+        if (!$field_storage_configs = \Drupal::entityManager()->getStorage('field_storage_config')->loadByProperties(['field_name' => $field_name])) {
+          continue;
+        }
+        else {
+          foreach ($field_storage_configs as $field_storage) {
+            $new_field_storage = $field_storage->toArray();
+            $new_field_storage['type'] = 'edtf';
+            $new_field_storage = FieldStorageConfig::create($new_field_storage);
+            $new_field_storage->original = $new_field_storage;
+            $new_field_storage->enforceIsNew(FALSE);
+            $new_field_storage->save();
+          }
+        }
+      }
+    }
+    $entity_form_display->save(TRUE);
+  }
+
+  // Find display configs.
+  foreach ($config_factory->listAll('core.entity_view_display.') as $entity_view_display_config_name) {
+    $entity_view_display = $config_factory->getEditable($entity_view_display_config_name);
+    $fields = $entity_view_display->get('content');
+    foreach ($fields as $field_name => $field_settings) {
+      if (isset($field_settings['type']) && ($field_settings['type'] === 'text_edtf_human' || $field_settings['type'] === 'text_edtf_iso8601')) {
+        // Update this view setting.
+        $entity_view_display->set("content.$field_name.type", 'edtf_default');
       }
     }
+    $entity_view_display->save(TRUE);
   }
 }
diff --git a/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.corporate_body.default.yml b/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.corporate_body.default.yml
index cf81ea8..f9f59b4 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.corporate_body.default.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.corporate_body.default.yml
@@ -40,7 +40,7 @@ content:
       strict_dates: false
       intervals: false
     third_party_settings: {  }
-    type: text_edtf
+    type: edtf_default
     region: content
   field_cat_date_end:
     weight: 5
@@ -48,7 +48,7 @@ content:
       strict_dates: false
       intervals: false
     third_party_settings: {  }
-    type: text_edtf
+    type: edtf_default
     region: content
   field_corp_alt_name:
     weight: 6
diff --git a/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.family.default.yml b/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.family.default.yml
index caead34..c5ff0a9 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.family.default.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.family.default.yml
@@ -38,7 +38,7 @@ content:
       strict_dates: false
       intervals: false
     third_party_settings: {  }
-    type: text_edtf
+    type: edtf_default
     region: content
   field_cat_date_end:
     weight: 9
@@ -46,7 +46,7 @@ content:
       strict_dates: false
       intervals: false
     third_party_settings: {  }
-    type: text_edtf
+    type: edtf_default
     region: content
   field_relationships:
     weight: 123
diff --git a/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.person.default.yml b/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.person.default.yml
index 9d7b8b9..82689d7 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.person.default.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/core.entity_form_display.taxonomy_term.person.default.yml
@@ -42,7 +42,7 @@ content:
       strict_dates: false
       intervals: false
     third_party_settings: {  }
-    type: text_edtf
+    type: edtf_default
     region: content
   field_cat_date_end:
     weight: 27
@@ -50,7 +50,7 @@ content:
       strict_dates: false
       intervals: false
     third_party_settings: {  }
-    type: text_edtf
+    type: edtf_default
     region: content
   field_person_alternate_names:
     weight: 3
diff --git a/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.corporate_body.default.yml b/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.corporate_body.default.yml
index 3e49437..3133cd5 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.corporate_body.default.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.corporate_body.default.yml
@@ -47,7 +47,7 @@ content:
       day_format: dd
       season_hemisphere: north
     third_party_settings: {  }
-    type: text_edtf_human
+    type: edtf_default
     region: content
   field_cat_date_end:
     weight: 3
@@ -59,7 +59,7 @@ content:
       day_format: dd
       season_hemisphere: north
     third_party_settings: {  }
-    type: text_edtf_human
+    type: edtf_default
     region: content
   field_corp_alt_name:
     weight: 4
diff --git a/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.family.default.yml b/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.family.default.yml
index 05f66fd..05d4f07 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.family.default.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.family.default.yml
@@ -44,7 +44,7 @@ content:
       day_format: dd
       season_hemisphere: north
     third_party_settings: {  }
-    type: text_edtf_human
+    type: edtf_default
     region: content
   field_cat_date_end:
     weight: 9
@@ -56,7 +56,7 @@ content:
       day_format: dd
       season_hemisphere: north
     third_party_settings: {  }
-    type: text_edtf_human
+    type: edtf_default
     region: content
   field_relationships:
     weight: 11
diff --git a/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.person.default.yml b/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.person.default.yml
index c53f09e..5f7245f 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.person.default.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/core.entity_view_display.taxonomy_term.person.default.yml
@@ -47,7 +47,7 @@ content:
       day_format: dd
       season_hemisphere: north
     third_party_settings: {  }
-    type: text_edtf_human
+    type: edtf_default
     region: content
   field_cat_date_end:
     weight: 7
@@ -59,7 +59,7 @@ content:
       day_format: dd
       season_hemisphere: north
     third_party_settings: {  }
-    type: text_edtf_human
+    type: edtf_default
     region: content
   field_person_alternate_names:
     weight: 3
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_begin.yml b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_begin.yml
index 556e6ce..723c616 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_begin.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_begin.yml
@@ -15,4 +15,4 @@ translatable: false
 default_value: {  }
 default_value_callback: ''
 settings: {  }
-field_type: string
+field_type: edtf
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_end.yml b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_end.yml
index f9cfe7c..cb67890 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_end.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.corporate_body.field_cat_date_end.yml
@@ -15,4 +15,4 @@ translatable: true
 default_value: {  }
 default_value_callback: ''
 settings: {  }
-field_type: string
+field_type: edtf
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_begin.yml b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_begin.yml
index 2428ea4..58ab96f 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_begin.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_begin.yml
@@ -15,4 +15,4 @@ translatable: false
 default_value: {  }
 default_value_callback: ''
 settings: {  }
-field_type: string
+field_type: edtf
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_end.yml b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_end.yml
index b92fa70..2db627d 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_end.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.family.field_cat_date_end.yml
@@ -15,4 +15,4 @@ translatable: true
 default_value: {  }
 default_value_callback: ''
 settings: {  }
-field_type: string
+field_type: edtf
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_begin.yml b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_begin.yml
index 3f576b7..eb1064c 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_begin.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_begin.yml
@@ -15,4 +15,4 @@ translatable: false
 default_value: {  }
 default_value_callback: ''
 settings: {  }
-field_type: string
+field_type: edtf
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_end.yml b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_end.yml
index 99a3201..ca4e79f 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_end.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.field.taxonomy_term.person.field_cat_date_end.yml
@@ -15,4 +15,4 @@ translatable: false
 default_value: {  }
 default_value_callback: ''
 settings: {  }
-field_type: string
+field_type: edtf
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_begin.yml b/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_begin.yml
index 751d041..d1545e5 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_begin.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_begin.yml
@@ -6,7 +6,7 @@ dependencies:
 id: taxonomy_term.field_cat_date_begin
 field_name: field_cat_date_begin
 entity_type: taxonomy_term
-type: string
+type: edtf
 settings:
   max_length: 60
   is_ascii: false
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_end.yml b/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_end.yml
index 4191c39..76cb22f 100644
--- a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_end.yml
+++ b/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_cat_date_end.yml
@@ -6,7 +6,7 @@ dependencies:
 id: taxonomy_term.field_cat_date_end
 field_name: field_cat_date_end
 entity_type: taxonomy_term
-type: string
+type: edtf
 settings:
   max_length: 60
   is_ascii: false
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_corp_dissolution_date.yml b/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_corp_dissolution_date.yml
deleted file mode 100644
index 3eb84d0..0000000
--- a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_corp_dissolution_date.yml
+++ /dev/null
@@ -1,20 +0,0 @@
-langcode: en
-status: true
-dependencies:
-  module:
-    - taxonomy
-id: taxonomy_term.field_corp_dissolution_date
-field_name: field_corp_dissolution_date
-entity_type: taxonomy_term
-type: string
-settings:
-  max_length: 60
-  is_ascii: false
-  case_sensitive: false
-module: core
-locked: false
-cardinality: 1
-translatable: true
-indexes: {  }
-persist_with_no_fields: false
-custom_storage: false
diff --git a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_corp_founding_date.yml b/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_corp_founding_date.yml
deleted file mode 100644
index 55798c6..0000000
--- a/modules/controlled_access_terms_default_configuration/config/install/field.storage.taxonomy_term.field_corp_founding_date.yml
+++ /dev/null
@@ -1,20 +0,0 @@
-langcode: en
-status: true
-dependencies:
-  module:
-    - taxonomy
-id: taxonomy_term.field_corp_founding_date
-field_name: field_corp_founding_date
-entity_type: taxonomy_term
-type: string
-settings:
-  max_length: 60
-  is_ascii: false
-  case_sensitive: false
-module: core
-locked: false
-cardinality: 1
-translatable: true
-indexes: {  }
-persist_with_no_fields: false
-custom_storage: false
diff --git a/src/EDTFConverter.php b/src/EDTFConverter.php
index a1fd726..85a278e 100644
--- a/src/EDTFConverter.php
+++ b/src/EDTFConverter.php
@@ -54,7 +54,7 @@ class EDTFConverter extends CommonDataConverter {
    * @return string
    *   Returns the ISO 8601 timestamp.
    */
-  public static function dateIso8601Value(array $data) {
+  public static function datetimeIso8601Value(array $data) {
     $date = explode('/', $data['value'])[0];
 
     // Strip approximations/uncertainty.
@@ -67,13 +67,56 @@ public static function dateIso8601Value(array $data) {
     $date = str_replace('u', '0', $date);
 
     // Seasons map.
-    list($year, $month, $day) = explode('-', $date, 3);
+    return EDTFConverter::seasonsMap($date) . 'T00:00:00';
+
+  }
+
+  /**
+   * Converts an EDTF text field into an ISO 8601 timestamp string.
+   *
+   * It assumes the earliest valid date for approximations and intervals.
+   *
+   * @param array $data
+   *   The array containing the 'value' element.
+   *
+   * @return string
+   *   Returns the ISO 8601 date.
+   */
+  public static function dateIso8601Value(array $data) {
+    $date = explode('/', $data['value'])[0];
+
+    // Strip approximations/uncertainty.
+    $date = str_replace(['?', '~'], '', $date);
+
+    // Remove unspecified.
+    // Month/day.
+    $date = str_replace('-uu', '', $date);
+    // Zero-Year in decade/century.
+    $date = str_replace('u', '0', $date);
+
+    // Seasons map.
+    return EDTFConverter::seasonsMap($date);
+
+  }
+
+  /**
+   * Converts a numeric season into a numeric month.
+   *
+   * @param string $date
+   *   The date string to convert.
+   *
+   * @return string
+   *   Returns the ISO 8601 date with the correct month.
+   */
+  protected static function seasonsMap(string $date) {
+    $date_parts[] = explode('-', $date, 3);
     // Digit Seasons.
-    if (in_array($month, ['21', '22', '23', '24'])) {
+    if ((count($date_parts) > 1) &&
+        in_array($date_parts[1], ['21', '22', '23', '24'])) {
       // TODO: Make hemisphere seasons configurable.
       $season_mapping = $seasonMapNorth;
-      $month = $season_mapping[$month];
-      $date = implode('-', array_filter([$year, $month, $day]));
+      $date_parts[1] = $season_mapping[$date_parts[1]];
+      $date = implode('-', array_filter($date_parts));
     }
 
     return $date;
diff --git a/src/Plugin/Field/FieldFormatter/TextEDTFHumanFormatter.php b/src/Plugin/Field/FieldFormatter/EDTFFormatter.php
similarity index 97%
rename from src/Plugin/Field/FieldFormatter/TextEDTFHumanFormatter.php
rename to src/Plugin/Field/FieldFormatter/EDTFFormatter.php
index f6a4f5b..0720c36 100644
--- a/src/Plugin/Field/FieldFormatter/TextEDTFHumanFormatter.php
+++ b/src/Plugin/Field/FieldFormatter/EDTFFormatter.php
@@ -7,19 +7,19 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- * Plugin implementation of the 'TextEDTFHumanFormatter'.
+ * Plugin implementation of the 'TextEDTFFormatter'.
  *
  * Only supports EDTF through level 1.
  *
  * @FieldFormatter(
- *   id = "text_edtf_human",
- *   label = @Translation("EDTF (L1) for Humans"),
+ *   id = "edtf_default",
+ *   label = @Translation("Default EDTF formatter"),
  *   field_types = {
- *     "string"
+ *     "edtf"
  *   }
  * )
  */
-class TextEDTFHumanFormatter extends FormatterBase {
+class EDTFFormatter extends FormatterBase {
 
   /**
    * Month/Season to text map.
@@ -158,7 +158,7 @@ public function settingsForm(array $form, FormStateInterface $form_state) {
       '#title' => t('Hemisphere Seasons'),
       '#type' => 'select',
       '#default_value' => $this->getSetting('season_hemisphere'),
-      '#description' => t("Seasons don't have digit months so we map them 
+      '#description' => t("Seasons don't have digit months so we map them
                           to their respective equinox and solstice months.
                           Select a hemisphere to use for the mapping."),
       '#options' => [
diff --git a/src/Plugin/Field/FieldFormatter/TextEDTFiso8601.php b/src/Plugin/Field/FieldFormatter/TextEDTFiso8601.php
deleted file mode 100644
index 1dfaf5d..0000000
--- a/src/Plugin/Field/FieldFormatter/TextEDTFiso8601.php
+++ /dev/null
@@ -1,138 +0,0 @@
-<?php
-
-namespace Drupal\controlled_access_terms\Plugin\Field\FieldFormatter;
-
-use Drupal\Core\Field\FormatterBase;
-use Drupal\Core\Field\FieldItemListInterface;
-use Drupal\Core\Form\FormStateInterface;
-
-/**
- * Plugin implementation of the 'TextEDTFiso8601'.
- *
- * Only supports EDTF through level 1.
- *
- * Uses first interval. An option to select which interval
- * could come in the future.
- *
- * Approximation and uncertainty is dropped.
- * Only supports earlist date in range of unspecified dates.
- * Max dates could be added in future versions.
- *
- * @FieldFormatter(
- *   id = "text_edtf_iso8601",
- *   label = @Translation("EDTF (L1) ISO 8601"),
- *   field_types = {
- *     "string"
- *   }
- * )
- */
-class TextEDTFiso8601 extends FormatterBase {
-
-  /**
-   * Northern hemisphere season map.
-   *
-   * @var array
-   */
-  private $seasonMapNorth = [
-  // Spring => March.
-    '21' => '03',
-  // Summer => June.
-    '22' => '06',
-  // Autumn => September.
-    '23' => '09',
-  // Winter => December.
-    '24' => '12',
-  ];
-
-  /**
-   * Southern hemisphere season map.
-   *
-   * @var array
-   */
-  private $seasonMapSouth = [
-  // Spring => September.
-    '21' => '03',
-  // Summer => December.
-    '22' => '06',
-  // Autumn => March.
-    '23' => '09',
-  // Winter => June.
-    '24' => '12',
-  ];
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function defaultSettings() {
-    return [
-    // Northern bias, sorry.
-      'season_hemisphere' => 'north',
-    ] + parent::defaultSettings();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function settingsForm(array $form, FormStateInterface $form_state) {
-    $form['season_hemisphere'] = [
-      '#title' => t('Hemisphere Seasons'),
-      '#type' => 'select',
-      '#default_value' => $this->getSetting('season_hemisphere'),
-      '#description' => t("Seasons aren't currently supported by iso 8601.
-                          We map them to their respective equinox and
-                          solstice months. Select a hemisphere to use for
-                          the mapping."),
-      '#options' => [
-        'north' => t('Northern Hemisphere'),
-        'south' => t('Southern Hemisphere'),
-      ],
-    ];
-    return $form;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function settingsSummary() {
-    $summary = [];
-    if ($this->getSetting('strict_dates') === 'south') {
-      $summary[] = t('Seasons mapped to the southern hemisphere.');
-    }
-    return $summary;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function viewElements(FieldItemListInterface $items, $langcode) {
-    $element = [];
-    $settings = $this->getSettings();
-
-    foreach ($items as $delta => $item) {
-      // Interval.
-      list($begin, $end) = explode('/', $item->value);
-      // End is currently ignored.
-      // Strip approximations/uncertainty.
-      $begin = str_replace(['?', '~'], '', $begin);
-
-      // Replace unspecified.
-      // Month/day.
-      $begin = str_replace('-uu', '-01', $begin);
-      // Zero-Year in decade/century.
-      $begin = str_replace('u', '0', $begin);
-
-      // Seasons map.
-      list($year, $month, $day) = explode('-', $begin, 3);
-      // Digit Seasons.
-      if (in_array($month, ['21', '22', '23', '24'])) {
-        $season_mapping = ($settings['season_hemisphere'] === 'north' ? $this->seasonMapNorth : $this->seasonMapSouth);
-        $month = $season_mapping[$month];
-        $begin = implode('-', array_filter([$year, $month, $day]));
-      }
-
-      $element[$delta] = ['#markup' => $begin];
-    }
-    return $element;
-  }
-
-}
diff --git a/src/Plugin/Field/FieldType/ExtendedDateTimeFormat.php b/src/Plugin/Field/FieldType/ExtendedDateTimeFormat.php
new file mode 100644
index 0000000..900e4d2
--- /dev/null
+++ b/src/Plugin/Field/FieldType/ExtendedDateTimeFormat.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Drupal\controlled_access_terms\Plugin\Field\FieldType;
+
+use Drupal\Core\Field\Plugin\Field\FieldType\StringItem;
+
+/**
+ * Implements a Extended DateTime Format field.
+ *
+ * @FieldType(
+ *   id = "edtf",
+ *   label = @Translation("EDTF, level 1"),
+ *   module = "controlled_access_terms",
+ *   description = @Translation("Extended Date Time Format field"),
+ *   default_formatter = "edtf_default",
+ *   default_widget = "edtf_default",
+ * )
+ */
+class ExtendedDateTimeFormat extends StringItem {
+
+}
diff --git a/src/Plugin/Field/FieldWidget/TextEDTFWidget.php b/src/Plugin/Field/FieldWidget/EDTFWidget.php
similarity index 97%
rename from src/Plugin/Field/FieldWidget/TextEDTFWidget.php
rename to src/Plugin/Field/FieldWidget/EDTFWidget.php
index 905f9f9..8d59cca 100644
--- a/src/Plugin/Field/FieldWidget/TextEDTFWidget.php
+++ b/src/Plugin/Field/FieldWidget/EDTFWidget.php
@@ -8,7 +8,7 @@
 use Drupal\Core\Form\FormStateInterface;
 
 /**
- * Plugin implementation of the 'text_edtf' widget.
+ * Plugin implementation of the 'edtf' widget.
  *
  * Validates text values for compliance with EDTF 1.0, level 1.
  * http://www.loc.gov/standards/datetime/pre-submission.html.
@@ -16,14 +16,14 @@
  * // TODO: maybe some day support level 2.
  *
  * @FieldWidget(
- *   id = "text_edtf",
- *   label = @Translation("Extended Date Time Format, Level 1"),
+ *   id = "edtf_default",
+ *   label = @Translation("Default EDTF widget"),
  *   field_types = {
- *     "string"
+ *     "edtf"
  *   }
  * )
  */
-class TextEDTFWidget extends WidgetBase {
+class EDTFWidget extends WidgetBase {
 
   /**
    * {@inheritdoc}
@@ -40,7 +40,7 @@ public static function defaultSettings() {
    */
   public function settingsForm(array $form, FormStateInterface $form_state) {
     $description_string = $this->t(
-        'Negative dates, and the level 1 features unspecified dates, 
+        'Negative dates, and the level 1 features unspecified dates,
         extended years, and seasons
         are not supported with strict date checking.'
     );
diff --git a/src/Plugin/Field/FieldWidget/TextDateWidget.php b/src/Plugin/Field/FieldWidget/TextDateWidget.php
deleted file mode 100644
index fe1ab5e..0000000
--- a/src/Plugin/Field/FieldWidget/TextDateWidget.php
+++ /dev/null
@@ -1,106 +0,0 @@
-<?php
-
-namespace Drupal\controlled_access_terms\Plugin\Field\FieldWidget;
-
-use Datetime;
-use Drupal\Core\Field\FieldItemListInterface;
-use Drupal\Core\Field\WidgetBase;
-use Drupal\Core\Form\FormStateInterface;
-
-/**
- * Plugin implementation of the 'text_date' widget.
- *
- * @FieldWidget(
- *   id = "text_date",
- *   label = @Translation("Date as Text"),
- *   field_types = {
- *     "string"
- *   }
- * )
- */
-class TextDateWidget extends WidgetBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function defaultSettings() {
-    return [
-      // Assign a default date format of.
-      'date_format' => 'Y-m-d',
-      'strict_dates' => TRUE,
-    ] + parent::defaultSettings();
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function settingsForm(array $form, FormStateInterface $form_state) {
-    $element = parent::settingsForm($form, $form_state);
-    $element['date_format'] = [
-      '#type' => 'textfield',
-      '#title' => $this->t('PHP DateTime Format String.'),
-      '#description' => $this->t('See <a href="@phpdate" target="_blank">PHP DateTime Documentation</a> for details.', ['@phpdate' => 'http://php.net/manual/en/datetime.createfromformat.php']),
-      '#default_value' => $this->getSetting('date_format'),
-    ];
-    $element['strict_dates'] = [
-      '#type' => 'checkbox',
-      '#title' => $this->t('Ensure date values are valid.'),
-      '#default_value' => $this->getSetting('strict_dates'),
-    ];
-    return $element;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function settingsSummary() {
-    $summary = [];
-
-    $summary[] = t('Date Format: @format', ['@format' => $this->getSetting('date_format')]);
-
-    if ($this->getSetting('strict_dates')) {
-      $summary[] = t('Strict dates enabled');
-    }
-
-    return $summary;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
-    $element['value'] = $element + [
-      '#type' => 'textfield',
-      '#default_value' => isset($items[$delta]->value) ? $items[$delta]->value : NULL,
-      '#placeholder' => $this
-        ->getSetting('placeholder'),
-      '#element_validate' => [
-        [$this, 'validate'],
-      ],
-    ];
-    return $element;
-  }
-
-  /**
-   * Validate date format compliance.
-   */
-  public function validate($element, FormStateInterface $form_state) {
-    $value = $element['#value'];
-    if (strlen($value) == 0) {
-      $form_state->setValueForElement($element, '');
-      return;
-    }
-    $date_format = $this->getSetting('date_format');
-    $date = DateTime::createFromFormat($date_format, $value);
-    if (!$date) {
-      $form_state->setError($element, t("Date must match the pattern @format",
-        ['@format' => $date_format]));
-    }
-    $errors = DateTime::getLastErrors();
-    if ($this->getSetting('strict_dates') && !empty($errors['warning_count'])) {
-      $form_state->setError($element, t('Strictly speaking, the date "@value" is invalid!',
-        ['@value' => $value]));
-    }
-  }
-
-}