From 33f2d6f5381a41105fcc1c57fbd2c7fc7378856b Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Tue, 11 Apr 2023 09:36:36 -0400
Subject: [PATCH 01/13] start work

---
 spec.bs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/spec.bs b/spec.bs
index 992b1e20..5552ae94 100644
--- a/spec.bs
+++ b/spec.bs
@@ -86,6 +86,9 @@ spec: RFC8941; urlPrefix: https://www.rfc-editor.org/rfc/rfc8941.html
     text: structured header; url: #section-1
     for: structured header
       text: token; url: name-tokens
+spec: CSS; urlPrefix: https://www.w3.org/TR/cssom-view-1/
+  type: dfn
+    text: scroll a target into view; url: #scroll-an-element-into-view
 </pre>
 
 <style>
@@ -784,3 +787,13 @@ specification adds another value for fenced frames:
 
 : "`fencedframe`"
 :: This [=navigable=] is displaying a <{fencedframe}>'s content
+
+<h3 id=cssom-monkeypatch>CSSOM View</h3>
+
+The <a href=https://www.w3.org/TR/cssom-view-1>CSSOM View Module</a> defines scroll bubbling behavior
+through the [=scroll a target into view=] algorithm. Our specification modifies it to not allow
+scrolling a target into view if it is inside of a fenced frame.
+
+Modify the [=scroll a target into view=] algorithm to add a step after step 1 that reads:
+
+// PAHACER: add this
\ No newline at end of file

From bba7b7c638c42942eedea346b6e0fb4b3b5e7ddd Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Tue, 11 Apr 2023 11:26:54 -0400
Subject: [PATCH 02/13] complete monkey patches

---
 spec.bs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/spec.bs b/spec.bs
index 5552ae94..051d1950 100644
--- a/spec.bs
+++ b/spec.bs
@@ -89,6 +89,7 @@ spec: RFC8941; urlPrefix: https://www.rfc-editor.org/rfc/rfc8941.html
 spec: CSS; urlPrefix: https://www.w3.org/TR/cssom-view-1/
   type: dfn
     text: scroll a target into view; url: #scroll-an-element-into-view
+    text: run the scroll steps; url: document-run-the-scroll-steps
 </pre>
 
 <style>
@@ -794,6 +795,18 @@ The <a href=https://www.w3.org/TR/cssom-view-1>CSSOM View Module</a> defines scr
 through the [=scroll a target into view=] algorithm. Our specification modifies it to not allow
 scrolling a target into view if it is inside of a fenced frame.
 
-Modify the [=scroll a target into view=] algorithm to add a step after step 1 that reads:
+Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
 
-// PAHACER: add this
\ No newline at end of file
+2. If the <var ignore=''>target</var>-associated {{Document}}'s [=node navigable=]'s
+   [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=], terminate these steps.
+3. If the <var ignore=''>target</var>-associated {{Document}}'s [=Document/ancestor navigables=] contains
+   a [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
+   terminate these steps.
+
+Modify the [=run the scroll steps=] algorithm to add a check after step 1.1 that reads:
+
+2. If <var ignore=''>target</var> is a {{Document}} whose [=node navigable=]'s
+   [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
+   continue.
+
+Note: This ensures that scroll events do not affect fenced frames.

From 660ba63b80eedbf08b5d924b8292e2f90fad310c Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Thu, 18 May 2023 11:57:44 -0400
Subject: [PATCH 03/13] remove unnecessary exports and fix logic

---
 spec.bs | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/spec.bs b/spec.bs
index f749c886..a5d210aa 100644
--- a/spec.bs
+++ b/spec.bs
@@ -144,10 +144,6 @@ spec: RFC8941; urlPrefix: https://www.rfc-editor.org/rfc/rfc8941.html
     text: structured header; url: #section-1
     for: structured header
       text: token; url: name-tokens
-spec: CSS; urlPrefix: https://www.w3.org/TR/cssom-view-1/
-  type: dfn
-    text: scroll a target into view; url: #scroll-an-element-into-view
-    text: run the scroll steps; url: document-run-the-scroll-steps
 spec: permissions-policy; urlPrefix: https://w3c.github.io/webappsec-permissions-policy
   type: dfn
     text: ASCII-serialized policy directive; url: serialized-policy-directive
@@ -2258,9 +2254,9 @@ Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 t
    a [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
    terminate these steps.
 
-Modify the [=run the scroll steps=] algorithm to add a check after step 1.1 that reads:
+Modify the [=Document/run the scroll steps=] algorithm to add a check before step 1.1 that reads:
 
-2. If <var ignore=''>target</var> is a {{Document}} whose [=node navigable=]'s
+1. If <var ignore=''>target</var> is a {{Document}} whose [=node navigable=]'s
    [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
    continue.
 

From 4d66e3ec950022246159c6b5f583ed0f4176ea4e Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Mon, 22 May 2023 16:49:14 -0400
Subject: [PATCH 04/13] explain why we can't allow existing behavior

---
 spec.bs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/spec.bs b/spec.bs
index a5d210aa..04f23739 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2242,9 +2242,11 @@ achieve the outcomes described in the above explanatory content.
 
 <h3 id=cssom-monkeypatch>CSSOM View</h3>
 
-The <a href=https://www.w3.org/TR/cssom-view-1>CSSOM View Module</a> defines scroll bubbling behavior
-through the [=scroll a target into view=] algorithm. Our specification modifies it to not allow
-scrolling a target into view if it is inside of a fenced frame.
+The <a href=https://www.w3.org/TR/cssom-view-1>CSSOM View Module</a> defines scroll bubbling
+behavior through the [=scroll a target into view=] algorithm. Our specification modifies it to not
+allow scrolling a target into view if it is inside of a fenced frame. This is done because the
+{{Element/scrollIntoView()}} method is an event that can both be triggered from and observed by the
+web platform, which can open a side channel between a fenced frame and its embedder.
 
 Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
 

From 82df0f1ea493a2b4ee4e454f09e40854351e183a Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Wed, 31 May 2023 10:11:43 -0400
Subject: [PATCH 05/13] address review comments

---
 spec.bs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/spec.bs b/spec.bs
index 04f23739..8ca13c32 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2242,7 +2242,7 @@ achieve the outcomes described in the above explanatory content.
 
 <h3 id=cssom-monkeypatch>CSSOM View</h3>
 
-The <a href=https://www.w3.org/TR/cssom-view-1>CSSOM View Module</a> defines scroll bubbling
+The [[!CSSOM-VIEW]] module defines scroll bubbling
 behavior through the [=scroll a target into view=] algorithm. Our specification modifies it to not
 allow scrolling a target into view if it is inside of a fenced frame. This is done because the
 {{Element/scrollIntoView()}} method is an event that can both be triggered from and observed by the
@@ -2250,15 +2250,15 @@ web platform, which can open a side channel between a fenced frame and its embed
 
 Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
 
-2. If the <var ignore=''>target</var>-associated {{Document}}'s [=node navigable=]'s
+2. If the <var ignore>target</var>-associated {{Document}}'s [=node navigable=]'s
    [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=], terminate these steps.
-3. If the <var ignore=''>target</var>-associated {{Document}}'s [=Document/ancestor navigables=] contains
+3. If the <var ignore>target</var>-associated {{Document}}'s [=Document/ancestor navigables=] contains
    a [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
    terminate these steps.
 
 Modify the [=Document/run the scroll steps=] algorithm to add a check before step 1.1 that reads:
 
-1. If <var ignore=''>target</var> is a {{Document}} whose [=node navigable=]'s
+1. If <var ignore>target</var> is a {{Document}} whose [=node navigable=]'s
    [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
    continue.
 

From 578020051811ac9e4384f84c80e4b97ce2fcc529 Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Fri, 2 Jun 2023 13:09:07 -0400
Subject: [PATCH 06/13] fix formatting

---
 spec.bs | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/spec.bs b/spec.bs
index 8ca13c32..a0f543fb 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2250,16 +2250,16 @@ web platform, which can open a side channel between a fenced frame and its embed
 
 Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
 
-2. If the <var ignore>target</var>-associated {{Document}}'s [=node navigable=]'s
-   [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=], terminate these steps.
-3. If the <var ignore>target</var>-associated {{Document}}'s [=Document/ancestor navigables=] contains
-   a [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
-   terminate these steps.
+2. If the <var ignore>target</var>-associated {{Document}}'s [=node navigable=]'s [=navigable/
+   traversable navigable=] is a [=fenced navigable container/fenced navigable=], terminate these
+   steps.
+3. If the <var ignore>target</var>-associated {{Document}}'s [=Document/ancestor navigables=]
+   contains a [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable
+   container/fenced navigable=], terminate these steps.
 
 Modify the [=Document/run the scroll steps=] algorithm to add a check before step 1.1 that reads:
 
-1. If <var ignore>target</var> is a {{Document}} whose [=node navigable=]'s
-   [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
-   continue.
+1. If <var ignore>target</var> is a {{Document}} whose [=node navigable=]'s [=navigable/traversable
+   navigable=] is a [=fenced navigable container/fenced navigable=], continue.
 
 Note: This ensures that scroll events do not affect fenced frames.

From 9150a39a7ac4e5738ce28a4f4c639a9a8749e74d Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Mon, 5 Jun 2023 14:59:28 -0400
Subject: [PATCH 07/13] fix formatting

---
 spec.bs | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/spec.bs b/spec.bs
index b361dec2..80eadf3f 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2446,11 +2446,11 @@ algorithms to achieve the outcomes described in the above explanatory content.
 
 <h3 id=cssom-monkeypatch>CSSOM View</h3>
 
-The [[!CSSOM-VIEW]] module defines scroll bubbling
-behavior through the [=scroll a target into view=] algorithm. Our specification modifies it to not
-allow scrolling a target into view if it is inside of a fenced frame. This is done because the
-{{Element/scrollIntoView()}} method is an event that can both be triggered from and observed by the
-web platform, which can open a side channel between a fenced frame and its embedder.
+The [[!CSSOM-VIEW]] module defines scroll bubbling behavior through the [=scroll a target into
+view=] algorithm. Our specification modifies it to not allow scrolling a target into view if it is
+inside of a fenced frame. This is done because the {{Element/scrollIntoView()}} method is an event
+that can both be triggered from and observed by the web platform, which can open a side channel
+between a fenced frame and its embedder.
 
 Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
 

From cf3fd0f1d78f42f7af2e09dbc72aec65bd82442f Mon Sep 17 00:00:00 2001
From: Dominic Farolino <domfarolino@gmail.com>
Date: Tue, 6 Jun 2023 07:40:09 +0300
Subject: [PATCH 08/13] Wording

---
 spec.bs | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/spec.bs b/spec.bs
index 80eadf3f..aeea8b57 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2446,11 +2446,11 @@ algorithms to achieve the outcomes described in the above explanatory content.
 
 <h3 id=cssom-monkeypatch>CSSOM View</h3>
 
-The [[!CSSOM-VIEW]] module defines scroll bubbling behavior through the [=scroll a target into
-view=] algorithm. Our specification modifies it to not allow scrolling a target into view if it is
-inside of a fenced frame. This is done because the {{Element/scrollIntoView()}} method is an event
-that can both be triggered from and observed by the web platform, which can open a side channel
-between a fenced frame and its embedder.
+The [[!CSSOM-VIEW]] specification defines scroll bubbling behavior through the [=scroll a target
+into view=] algorithm. Our specification modifies it to not allow scrolling a target into view if it
+is inside of a fenced frame. This is done because the {{Element/scrollIntoView()}} method is an
+event that can both be invoked from and observed by script, which can open a communication side
+channel between a <{fencedframe}> and its embedder.
 
 Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
 

From dbd7e394291190a1e8965f5e8a059e43678b4c64 Mon Sep 17 00:00:00 2001
From: Dominic Farolino <domfarolino@gmail.com>
Date: Tue, 6 Jun 2023 07:51:42 +0300
Subject: [PATCH 09/13] Fixes

---
 spec.bs | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/spec.bs b/spec.bs
index aeea8b57..9f98b47c 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2452,19 +2452,24 @@ is inside of a fenced frame. This is done because the {{Element/scrollIntoView()
 event that can both be invoked from and observed by script, which can open a communication side
 channel between a <{fencedframe}> and its embedder.
 
-Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that reads:
+<div algorithm=scroll-target-into-view>
+  Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that read:
 
-2. If the <var ignore>target</var>-associated {{Document}}'s [=node navigable=]'s [=navigable/
-   traversable navigable=] is a [=fenced navigable container/fenced navigable=], terminate these
-   steps.
-3. If the <var ignore>target</var>-associated {{Document}}'s [=Document/ancestor navigables=]
-   contains a [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable
-   container/fenced navigable=], terminate these steps.
+  2. If |target|'s associated {{Document}}'s [=node navigable=]'s [=navigable/traversable
+     navigable=] is a [=fenced navigable container/fenced navigable=], terminate these steps.
 
-Modify the [=Document/run the scroll steps=] algorithm to add a check before step 1.1 that reads:
+  3. If |target|'s associated {{Document}}'s [=Document/ancestor navigables=] [list/contains=] a
+     [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable
+     container/fenced navigable=], terminate these steps.
+</div>
+
+<div algorithm=run-the-scroll-steps>
+  Modify the [=Document/run the scroll steps=] algorithm to add a check before step 1.1 that reads:
 
-1. If <var ignore>target</var> is a {{Document}} whose [=node navigable=]'s [=navigable/traversable
-   navigable=] is a [=fenced navigable container/fenced navigable=], continue.
+  1. If <var ignore>target</var> is a {{Document}} whose [=node navigable=]'s
+     [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
+     [=iteration/continue=].
+</div>
 
 Note: This ensures that scroll events do not affect fenced frames.
 

From 0bfca7a9597dd283ee8f7e78b79a3b1048045634 Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Fri, 21 Jul 2023 11:58:51 -0400
Subject: [PATCH 10/13] Refactor to match design document

---
 spec.bs | 36 ++++++++++++++++--------------------
 1 file changed, 16 insertions(+), 20 deletions(-)

diff --git a/spec.bs b/spec.bs
index 9f98b47c..61693145 100644
--- a/spec.bs
+++ b/spec.bs
@@ -230,6 +230,10 @@ spec: permissions-policy; urlPrefix: https://w3c.github.io/webappsec-permissions
   type: dfn
     for: permissions policy
       text: inherited policy; url: inherited-policy
+spec: css2; urlPrefix: https://www.w3.org/TR/CSS21/visuren.html
+  type: dfn
+    for: css2
+      text: viewport; url: viewport
 </pre>
 
 <style>
@@ -2446,33 +2450,25 @@ algorithms to achieve the outcomes described in the above explanatory content.
 
 <h3 id=cssom-monkeypatch>CSSOM View</h3>
 
-The [[!CSSOM-VIEW]] specification defines scroll bubbling behavior through the [=scroll a target
-into view=] algorithm. Our specification modifies it to not allow scrolling a target into view if it
-is inside of a fenced frame. This is done because the {{Element/scrollIntoView()}} method is an
-event that can both be invoked from and observed by script, which can open a communication side
-channel between a <{fencedframe}> and its embedder.
+The [[!CSSOM-VIEW]] specification defines the {{Element/scrollIntoView()}} method that calls the
+[=scroll a target into view=] algorithm. This will not only scroll the {{Element}} or
+[=css2/viewport=] to make the target visible, but will also scroll [=tree/ancestor=]s if necessary
+to make the target visible, essentially causing the scroll to "bubble up". This means that
+{{Element/scrollIntoView()}} performed in a [=child navigable=] or [=fenced navigable
+container/fenced navigable=] can be observed by its embedder, allowing for collusion across a fenced
+frame boundary. This section patches {{Element/scrollIntoView()}} to prevent that collusion at the
+expense of some functionality.
 
 <div algorithm=scroll-target-into-view>
-  Modify the [=scroll a target into view=] algorithm to add 2 steps after step 1 that read:
-
-  2. If |target|'s associated {{Document}}'s [=node navigable=]'s [=navigable/traversable
-     navigable=] is a [=fenced navigable container/fenced navigable=], terminate these steps.
+  Modify the [=scroll a target into view=] algorithm to add a step at the end of the algorithm that reads:
 
-  3. If |target|'s associated {{Document}}'s [=Document/ancestor navigables=] [list/contains=] a
-     [=navigable=] whose [=navigable/traversable navigable=] is a [=fenced navigable
+  14. If <var ignore>scrolling box</var>'s associated {{Element}} or [=css2/viewport=]'s associated
+     {{Document}}'s [=node navigable=]'s [=navigable/traversable navigable=] is a [=fenced navigable
      container/fenced navigable=], terminate these steps.
-</div>
 
-<div algorithm=run-the-scroll-steps>
-  Modify the [=Document/run the scroll steps=] algorithm to add a check before step 1.1 that reads:
-
-  1. If <var ignore>target</var> is a {{Document}} whose [=node navigable=]'s
-     [=navigable/traversable navigable=] is a [=fenced navigable container/fenced navigable=],
-     [=iteration/continue=].
+  Note: This allows scrolling to "bubble up" to a fenced frame boundary, but not cross it.
 </div>
 
-Note: This ensures that scroll events do not affect fenced frames.
-
 <h2 id=security-and-privacy>Security & Privacy Considerations</h2>
 
 This material is being upstreamed from our explainer into this specification, and in the meantime

From 96e7d5c1e401d503ce028db9735e75ac79652853 Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Mon, 31 Jul 2023 09:44:31 -0400
Subject: [PATCH 11/13] reword and fix alignment

---
 spec.bs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/spec.bs b/spec.bs
index 61693145..ae89e4a6 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2457,10 +2457,11 @@ to make the target visible, essentially causing the scroll to "bubble up". This
 {{Element/scrollIntoView()}} performed in a [=child navigable=] or [=fenced navigable
 container/fenced navigable=] can be observed by its embedder, allowing for collusion across a fenced
 frame boundary. This section patches {{Element/scrollIntoView()}} to prevent that collusion at the
-expense of some functionality.
+expense of some utility.
 
 <div algorithm=scroll-target-into-view>
-  Modify the [=scroll a target into view=] algorithm to add a step at the end of the algorithm that reads:
+  Modify the [=scroll a target into view=] algorithm to add a step at the end of the algorithm that
+  reads:
 
   14. If <var ignore>scrolling box</var>'s associated {{Element}} or [=css2/viewport=]'s associated
      {{Document}}'s [=node navigable=]'s [=navigable/traversable navigable=] is a [=fenced navigable

From c8390fde1a883a59846dfd23bfcb1751d0d8dc0d Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Mon, 31 Jul 2023 09:53:58 -0400
Subject: [PATCH 12/13] update intro to mention actual algorithm being patched

---
 spec.bs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/spec.bs b/spec.bs
index ae89e4a6..dffc4a8c 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2454,10 +2454,10 @@ The [[!CSSOM-VIEW]] specification defines the {{Element/scrollIntoView()}} metho
 [=scroll a target into view=] algorithm. This will not only scroll the {{Element}} or
 [=css2/viewport=] to make the target visible, but will also scroll [=tree/ancestor=]s if necessary
 to make the target visible, essentially causing the scroll to "bubble up". This means that
-{{Element/scrollIntoView()}} performed in a [=child navigable=] or [=fenced navigable
-container/fenced navigable=] can be observed by its embedder, allowing for collusion across a fenced
-frame boundary. This section patches {{Element/scrollIntoView()}} to prevent that collusion at the
-expense of some utility.
+{{Element/scrollIntoView()}} performed in a [=child navigable=] or [=fenced navigable container/
+fenced navigable=] can be observed by its embedder, allowing for collusion across a fenced frame
+boundary. This section patches the [=scroll a target into view=] algorithm to prevent that collusion
+at the expense of some utility.
 
 <div algorithm=scroll-target-into-view>
   Modify the [=scroll a target into view=] algorithm to add a step at the end of the algorithm that

From ca2a489f5d3b06b6dfe794b3d4f645c8295356e8 Mon Sep 17 00:00:00 2001
From: Liam Brady <blu2.5@me.com>
Date: Mon, 31 Jul 2023 12:54:31 -0400
Subject: [PATCH 13/13] remove ambiguity

---
 spec.bs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/spec.bs b/spec.bs
index dffc4a8c..f17ce358 100644
--- a/spec.bs
+++ b/spec.bs
@@ -2463,9 +2463,12 @@ at the expense of some utility.
   Modify the [=scroll a target into view=] algorithm to add a step at the end of the algorithm that
   reads:
 
-  14. If <var ignore>scrolling box</var>'s associated {{Element}} or [=css2/viewport=]'s associated
+  14. If <var ignore>scrolling box</var>'s associated {{Element}}'s associated {{Document}}'s [=node
+     navigable=]'s [=navigable/traversable navigable=] is a [=fenced navigable container/fenced
+     navigable=], or if <var ignore>scrolling box</var>'s associated [=css2/viewport=]'s associated
      {{Document}}'s [=node navigable=]'s [=navigable/traversable navigable=] is a [=fenced navigable
-     container/fenced navigable=], terminate these steps.
+     container/fenced navigable=], then let this be the last instance of this algorithm that stops
+     any further recursive instances that would otherwise follow.
 
   Note: This allows scrolling to "bubble up" to a fenced frame boundary, but not cross it.
 </div>