diff --git a/source b/source
index e3ad9bf4b9a..0764323ffa7 100755
--- a/source
+++ b/source
@@ -56291,7 +56291,8 @@ fur
      <li><p>For each character in the entry's name and value that cannot be expressed using the
      selected character encoding, replace the character by a string consisting of a U+0026 AMPERSAND
      character (&amp;), a U+0023 NUMBER SIGN character (#), one or more <span>ASCII digits</span>
-     representing the code point of the character in base ten, and finally a U+003B (;).</p></li>
+     representing the code point of the character in base ten, and finally a U+003B SEMICOLON
+     character (;).</p></li>
      <!-- we should say it should be the shortest possible string, no leading zeros. this whole step
           is asinine, though, so... -->
 
@@ -56318,10 +56319,21 @@ fur
     values must be encoded using the character encoding selected above.</p>
 
     <p>File names included in the generated <code>multipart/form-data</code> resource (as part of
-    file fields) must use the character encoding selected above, though the precise name may be
-    approximated if necessary (e.g. newlines could be removed from file names, quotes could be
-    changed to "%22", and characters not expressible in the selected character encoding could be
-    replaced by other characters).
+    file fields) must use the character encoding selected above. For each character in the entry's
+    file name that cannot be expressed using the selected character encoding, replace the character
+    by a string consisting of a U+0026 AMPERSAND character (&amp;), a U+0023 NUMBER SIGN character
+    (#), one or more <span>ASCII digits</span> representing the code point of the character in base
+    ten, and finally a U+003B (;).</p>
+
+    <p>Field names and file names included in the generated <code>multipart/form-data</code>
+    resource must undergo multipart parameter-value character replacement for syntactically
+    significant characters: for each character in the parameter value that is U+0022 QUOTATION MARK
+    ("), U+007F &lt;control&gt; (DEL) or any other <span data-x="control">control</span> in the
+    range U+0000-U+001F except U+001B &lt;control&gt; (ESC), replace the character by a string
+    consisting of a U+0025 PERCENT SIGN character (%) and two <span>ASCII hex digits</span>
+    representing the code point of the character in base sixteen, and replace each U+005C REVERSE
+    SOLIDUS character (\) with two consecutive U+005C REVERSE SOLIDUS characters (\\). U+001B
+    &lt;control&gt; (ESC) is preserved (passed through unquoted) for Web-compatible ISO-2022-JP.</p>
 
     <p>The boundary used by the user agent in generating the return value of this algorithm is the
     <dfn data-export=""><code>multipart/form-data</code> boundary string</dfn>. (This value is used