diff --git a/index.bs b/index.bs
index 921b2ead..e2f145b6 100644
--- a/index.bs
+++ b/index.bs
@@ -6353,8 +6353,10 @@ The following extended attributes are <dfn for="extended attributes">applicable
 [{{AllowResizable}}],
 [{{AllowShared}}],
 [{{Clamp}}],
-[{{EnforceRange}}], and
-[{{LegacyNullToEmptyString}}].
+[{{EnforceRange}}],
+[{{LegacyNullToEmptyString}}], and
+[{{StringContext}}].
+
 
 <div algorithm>
     The <dfn for="IDL type" lt="extended attribute associated with|extended attributes associated with">extended attributes associated with</dfn>
@@ -10259,6 +10261,39 @@ that does specify [{{SecureContext}}].
     </pre>
 </div>
 
+<h4 id="StringContext" extended-attribute lt="StringContext">[StringContext]</h4>
+
+If the [{{StringContext}}] [=extended attribute=] appears on {{DOMString}} or {{USVString}}, it
+modifies how the value is converted to the IDL type, causing additional value validation to
+adhere to the context the string is used in.
+
+The [{{StringContext}}] extended attribute must [=takes an identifier|take an identifier=]. The [=identifier=]
+must be one of "<code>TrustedHTML</code>", "<code>TrustedScript</code>", and "<code>TrustedScriptURL</code>".
+
+The [{{StringContext}}] extended attribute may only annotate a type of a [=regular attribute=] or
+a [=regular operation=] argument. A type annotated with the [{{StringContext}}]
+extended attribute must not appear in a [=read only=] attribute.
+
+A type that is not {{DOMString}} or {{USVString}} must not be [=extended attributes associated with|associated with=]
+the [{{StringContext}}] extended attribute.
+
+The [{{StringContext}}] extended attribute must not be used on only some of the [=overloaded|overloads=] of an
+[=overloaded=] [=operation=].
+
+<div class="example" id="example-7b5c2e9f">
+
+    In the following [=IDL fragment=],
+    a [=variadic=] [=operation=] is declared
+    that uses the [{{StringContext}}] [=extended attribute=]
+    on all its arguments:
+
+    <pre highlight="webidl">
+        interface Document {
+          void write([StringContext=TrustedHTML] DOMString... text);
+        };
+    </pre>
+</div>
+
 
 <h4 id="Unscopable" extended-attribute lt="Unscopable">[Unscopable]</h4>
 
@@ -11056,6 +11091,21 @@ allowed.  The security check takes the following three inputs:
 
 Note: The HTML Standard defines how a security check is performed. [[!HTML]]
 
+Certain algorithms are defined to
+<dfn id="dfn-validate-the-string-in-context" export>validate the string in context</dfn> on a given
+value. This check is used to determine whether a given value
+is appropriate for its {{StringContext}}. This validation takes the following four inputs:
+
+1.  the [=platform object=] on
+    which the operation invocation or attribute access is being done,
+1.  the value to validate,
+1.  the {{StringContext}} [=identifier=], and
+1.  the [=identifier=] of the operation or attribute.
+
+The algorithm returns an ECMAScript value, or [=JavaScript/throws=] a <l spec=ecmascript>{{TypeError}}</l>.
+
+Note: The HTML Standard defines how the validation is performed. [[!HTML]]
+
 
 <h3 id="js-overloads" oldids="es-overloads">Overload resolution algorithm</h3>
 
@@ -11092,8 +11142,16 @@ Note: The HTML Standard defines how a security check is performed. [[!HTML]]
             1.  If the argument at index |i| is declared with a [=optional argument/default value=],
                 then append to |values| that default value.
             1.  Otherwise, append to |values| the special value “missing”.
-        1.  Otherwise, append to |values| the result of [=converted to an IDL value|converting=]
-            |V| to IDL type |type|.
+        1. Otherwise:
+            1.  If |type| is an IDL type [=extended attribute associated with|associated with=] the
+                [{{StringContext}}] extended attribute, then set |V| to the result of performing
+                [=validate the string in context=], passing [=this=], |V|, the {{StringContext}}
+                extended attribute [=identifier=], and the [=identifier=]
+                of the [=operation=] or [=extended attribute=] of the first entry in |S|.
+
+                Note: That algorithm can [=JavaScript/throw=] a <l spec=ecmascript>{{TypeError}}</l>.
+            1.  Append to |values| the result of [=converted to an IDL value|converting=]
+                |V| to IDL type |type|.
         1.  Set |i| to |i| + 1.
     1.  If |i| = |d|, then:
         1.  Let |V| be |args|[|i|].
@@ -11292,8 +11350,16 @@ Note: The HTML Standard defines how a security check is performed. [[!HTML]]
             1.  If the argument at index |i| is declared with a [=optional argument/default value=],
                 then append to |values| that default value.
             1.  Otherwise, append to |values| the special value “missing”.
-        1.  Otherwise, append to |values| the result of
-            [=converted to an IDL value|converting=] |V| to IDL type |type|.
+        1. Otherwise:
+            1.  If |type| is an IDL type [=extended attribute associated with|associated with=] the
+                [{{StringContext}}] extended attribute, then set |V| to the result of performing
+                [=validate the string in context=], passing [=this=], |V|, the {{StringContext}}
+                extended attribute [=identifier=], and the [=identifier=]
+                of |callable|.
+
+                Note: That algorithm can [=JavaScript/throw=] a <l spec=ecmascript>{{TypeError}}</l>.
+            1.  Append to |values| the result of [=converted to an IDL value|converting=]
+                |V| to IDL type |type|.
         1.  Set |i| to |i| + 1.
     1.  While |i| is less than the number of arguments |callable| is declared to take:
         1.  If |callable|'s argument at index |i| is declared with a [=optional argument/default value=],
@@ -11982,8 +12048,14 @@ in which case they are exposed on every object that [=implements=] the interface
 
                 <dt>Otherwise</dt>
                 <dd>
-                    |idlValue| is the result of [=converted to an IDL value|converting=] |V| to an
-                    IDL value of |attribute|'s type.
+                    1.  If |attribute|'s type is [=extended attribute associated with|associated with=] the
+                        [{{StringContext}}] extended attribute, then set |V| to the result of performing
+                        [=validate the string in context=], passing [=this=], |V|, the {{StringContext}}
+                        extended attribute [=identifier=], and |id|.
+
+                        Note: That algorithm can [=JavaScript/throw=] a <l spec=ecmascript>{{TypeError}}</l>.
+                    1.  |idlValue| is the result of [=converted to an IDL value|converting=] |V| to an
+                        IDL value of |attribute|'s type.
                 </dd>
             </dl>