diff --git a/index.bs b/index.bs
index 2cc3ce42..ab808254 100644
--- a/index.bs
+++ b/index.bs
@@ -866,6 +866,44 @@ it is not always *sufficient*
 to protect users from invasive behaviours,
 and seeking [meaningful consent](#consent) is also important.
 
+<h3 id="handle-destroyed-contexts">Handle non-fully-active documents (and destroyed execution contexts)</h3>
+
+When an <{iframe}> (or similar) is removed or navigated,
+its document stops being [=Document/fully active=]
+and its [=ECMAScript/execution contexts=] can get destroyed.
+However, references to objects from that document
+can remain reachable from other documents
+or from other realms.
+
+Specifications should say what happens both at call time
+and after an operation has begun:
+otherwise background work may keep running after a page is gone,
+UI can hang, and user agents diverge in abort/cleanup behavior.
+
+If the [=relevant global object=]'s [=associated Document=]
+is not [=Document/fully active=] at call time,
+then [=throw=], or return [=a promise rejected with=],
+with {{InvalidStateError}}.
+
+If, after starting an asynchronous operation,
+that [=associated Document=] becomes non-[=Document/fully active=]
+or the [=relevant global object=]'s [=ECMAScript/execution context=] is destroyed,
+abort the operation and reject with {{AbortError}}.
+If the operation presents UI (e.g., a picker, chooser, or prompt),
+dismiss it when the context becomes non-[=Document/fully active=]
+and settle with {{AbortError}}.
+
+When [=queue a task|queueing=] subsequent work
+(e.g., for an event, settling a promise, a time-based operation),
+include an early exit:
+if the [=associated Document=] is not [=Document/fully active=],
+gracefully terminate the [=task=].
+Do not rely on garbage collection to define these semantics.
+
+See also: [[#support-non-fully-active]] for the BFCache case;
+most of the same principles apply to detached iframes
+and other torn-down [=All Execution Contexts/realms=].
+
 <h3 id="support-non-fully-active">Support non-fully active BFCached documents</h3>
 
 Specify how your feature behaves
@@ -1615,7 +1653,7 @@ Unlike dictionaries, interfaces:
     (i.e., one can check if  it is an `instanceof` a particular class on the global scope),
 
 Defining an interface also exposes it on the global scope, allowing for the specification of static methods.
-For example, the `canParse()` static method of the URL interface. 
+For example, the `canParse()` static method of the URL interface.
 
 ```JS
 if (URL.canParse(someURL)) {