Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 40262)
+++ src/wp-includes/formatting.php	(working copy)
@@ -1851,7 +1851,8 @@
 	$username = remove_accents( $username );
 	// Kill octets
 	$username = preg_replace( '|%([a-fA-F0-9][a-fA-F0-9])|', '', $username );
-	$username = preg_replace( '/&.+?;/', '', $username ); // Kill entities
+	// Remove HTML entities.
+	$username = preg_replace( '/&.+?;/', '', $username );
 
 	// If strict, reduce to ASCII for max portability.
 	if ( $strict )
@@ -1900,11 +1901,11 @@
 }
 
 /**
- * Sanitizes a title, or returns a fallback title.
+ * Sanitizes a string, HTML and PHP tags are stripped, and accents are removed, for use as a slug in a URL.
  *
- * Specifically, HTML and PHP tags are stripped. Further actions can be added
- * via the plugin API. If $title is empty and $fallback_title is set, the latter
- * will be used.
+ * Further actions can be added
+ * via the plugin API. If the sanitized version of $title is empty, and `$fallback_title` is set, 
+ * `$fallback_title` will be returned.
  *
  * @since 1.0.0
  *
@@ -1951,10 +1952,10 @@
 }
 
 /**
- * Sanitizes a title, replacing whitespace and a few other characters with dashes.
+ * Sanitizes a string
  *
- * Limits the output to alphanumeric characters, underscore (_) and dash (-).
- * Whitespace becomes a dash.
+ * Output is limited to to alphanumeric characters, underscore (_) and dash (-). 
+ * Various characters (including whitespace) are convered to dashes.
  *
  * @since 1.2.0
  *
@@ -2008,7 +2009,8 @@
 		$title = str_replace( '%c3%97', 'x', $title );
 	}
 
-	$title = preg_replace('/&.+?;/', '', $title); // kill entities
+	// Remove HTML entities. 
+ 	$title = preg_replace('/&.+?;/', '', $title);
 	$title = str_replace('.', '-', $title);
 
 	$title = preg_replace('/[^%a-z0-9 _-]/', '', $title);