diff --git a/core/lib/Drupal/Component/Render/EscapableString.php b/core/lib/Drupal/Component/Render/EscapableString.php
index eb44f16..ab42583 100644
--- a/core/lib/Drupal/Component/Render/EscapableString.php
+++ b/core/lib/Drupal/Component/Render/EscapableString.php
@@ -13,6 +13,9 @@
 /**
  * Escapes a string for display in markup.
  *
+ * This class can be used to provide theme engine-like late escaping
+ * functionality.
+ *
  * @ingroup sanitization
  */
 class EscapableString implements EscapableStringInterface {
diff --git a/core/lib/Drupal/Component/Render/MarkupInterface.php b/core/lib/Drupal/Component/Render/MarkupInterface.php
index 2da4e13..65ab29a 100644
--- a/core/lib/Drupal/Component/Render/MarkupInterface.php
+++ b/core/lib/Drupal/Component/Render/MarkupInterface.php
@@ -31,6 +31,9 @@
  * @see \Drupal\Component\Render\FormattableMarkup
  * @see \Drupal\Core\StringTranslation\TranslatableMarkup
  * @see \Drupal\views\Render\ViewsRenderPipelineMarkup
+ * @see twig_render_template()
+ * @see sanitization
+ * @see theme_render
  */
 interface MarkupInterface extends \JsonSerializable {
 
diff --git a/core/lib/Drupal/Component/Utility/SafeMarkup.php b/core/lib/Drupal/Component/Utility/SafeMarkup.php
index a64ac28..ec12419 100644
--- a/core/lib/Drupal/Component/Utility/SafeMarkup.php
+++ b/core/lib/Drupal/Component/Utility/SafeMarkup.php
@@ -12,24 +12,11 @@
 use Drupal\Component\Render\MarkupInterface;
 
 /**
- * Manages known safe strings for rendering at the theme layer.
+ * Contains deprecated functionality related to sanitization of markup.
  *
- * The Twig theme engine autoescapes string variables in the template, so it
- * is possible for a string of markup to become double-escaped. SafeMarkup
- * provides a store for known safe strings and methods to manage them
- * throughout the page request.
- *
- * Strings sanitized by self::checkPlain() and self::escape() are automatically
- * marked safe, as are markup strings created from @link theme_render render
- * arrays @endlink via drupal_render().
- *
- * This class should be limited to internal use only. Module developers should
- * instead use the appropriate
- * @link sanitization sanitization functions @endlink or the
- * @link theme_render theme and render systems @endlink so that the output can
- * can be themed, escaped, and altered properly.
- *
- * @deprecated Will be removed before Drupal 9.0.0.
+ * @deprecated Will be removed before Drupal 9.0.0. Use the appropriate
+ *   @link sanitization sanitization functions @endlink or the @link theme_render theme and render systems @endlink
+ *   so that the output can can be themed, escaped, and altered properly.
  *
  * @see TwigExtension::escapeFilter()
  * @see twig_render_template()
@@ -71,8 +58,6 @@ public static function isSafe($string, $strategy = 'html') {
    * @return \Drupal\Component\Render\EscapableStringInterface
    *   An EscapableString object that escapes when rendered to string.
    *
-   * @ingroup sanitization
-   *
    * @deprecated Will be removed before Drupal 9.0.0. Rely on Twig's
    *   auto-escaping feature, or use the @link theme_render #plain_text @endlink
    *   key when constructing a render array that contains plain text in order to
@@ -101,8 +86,6 @@ public static function checkPlain($text) {
    *   The formatted string, which is an instance of MarkupInterface unless
    *   sanitization of an unsafe argument was suppressed (see above).
    *
-   * @ingroup sanitization
-   *
    * @see \Drupal\Component\Render\FormattableMarkup::placeholderFormat()
    * @see \Drupal\Component\Render\FormattableMarkup
    *