diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index 30f0c42d7a42..6e4caefb8fcc 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -708,9 +708,11 @@ RestyleManager::ProcessRestyledFrames(nsStyleChangeList& aChangeList)
           nsIFrame* hintFrame = GetFrameForChildrenOnlyTransformHint(frame);
           nsIFrame* childFrame = hintFrame->GetFirstPrincipalChild();
           NS_ASSERTION(!nsLayoutUtils::GetNextContinuationOrIBSplitSibling(frame),
-                       "SVG frames should not have continuations or special siblings");
+                       "SVG frames should not have continuations "
+                       "or ib-split siblings");
           NS_ASSERTION(!nsLayoutUtils::GetNextContinuationOrIBSplitSibling(hintFrame),
-                       "SVG frames should not have continuations or special siblings");
+                       "SVG frames should not have continuations "
+                       "or ib-split siblings");
           for ( ; childFrame; childFrame = childFrame->GetNextSibling()) {
             NS_ABORT_IF_FALSE(childFrame->IsFrameOfType(nsIFrame::eSVG),
                               "Not expecting non-SVG children");
@@ -721,7 +723,8 @@ RestyleManager::ProcessRestyledFrames(nsStyleChangeList& aChangeList)
               mOverflowChangedTracker.AddFrame(childFrame);
             }
             NS_ASSERTION(!nsLayoutUtils::GetNextContinuationOrIBSplitSibling(childFrame),
-                         "SVG frames should not have continuations or special siblings");
+                         "SVG frames should not have continuations "
+                         "or ib-split siblings");
             NS_ASSERTION(childFrame->GetParent() == hintFrame,
                          "SVG child frame not expected to have different parent");
           }
@@ -1009,7 +1012,7 @@ RestyleManager::AttributeChanged(Element* aElement,
 
     // let the frame deal with it now, so we don't have to deal later
     primaryFrame->AttributeChanged(aNameSpaceID, aAttribute, aModType);
-    // XXXwaterson should probably check for special IB siblings
+    // XXXwaterson should probably check for IB split siblings
     // here, and propagate the AttributeChanged notification to
     // them, as well. Currently, inline frames don't do anything on
     // this notification, so it's not that big a deal.
@@ -1773,16 +1776,18 @@ static nsIFrame*
 GetPrevContinuationWithPossiblySameStyle(nsIFrame* aFrame)
 {
   // Account for {ib} splits when looking for "prevContinuation".  In
-  // particular, for the first-continuation of a part of an {ib} split we
-  // want to use the special prevsibling of the special prevsibling of
-  // aFrame, which should have the same style context as aFrame itself.
-  // In particular, if aFrame is the first continuation of an inline part
-  // of an {ib} split then its special prevsibling is a block, and the
-  // special prevsibling of _that_ is an inline, just like aFrame.
-  // Similarly, if aFrame is the first continuation of a block part of an
-  // {ib} split (an {ib} wrapper block), then its special prevsibling is
-  // an inline and the special prevsibling of that is either another {ib}
-  // wrapper block block or null.
+  // particular, for the first-continuation of a part of an {ib} split
+  // we want to use the previous ib-split sibling of the previous
+  // ib-split sibling of aFrame, which should have the same style
+  // context as aFrame itself.  In particular, if aFrame is the first
+  // continuation of an inline part of a block-in-inline split then its
+  // previous ib-split sibling is a block, and the previous ib-split
+  // sibling of _that_ is an inline, just like aFrame.  Similarly, if
+  // aFrame is the first continuation of a block part of an
+  // block-in-inline split (a block-in-inline wrapper block), then its
+  // previous ib-split sibling is an inline and the previous ib-split
+  // sibling of that is either another block-in-inline wrapper block box
+  // or null.
   nsIFrame *prevContinuation = aFrame->GetPrevContinuation();
   if (!prevContinuation &&
       (aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
@@ -1804,7 +1809,7 @@ GetPrevContinuationWithPossiblySameStyle(nsIFrame* aFrame)
 }
 
 /**
- * Get the previous continuation or similar special sibling (assuming
+ * Get the previous continuation or similar ib-split sibling (assuming
  * block/inline alternation), conditionally on it having the same style.
  * This assumes that we're not between resolving the two (i.e., that
  * they're both already resolved.
@@ -1829,7 +1834,7 @@ GetPrevContinuationWithSameStyle(nsIFrame* aFrame)
 }
 
 /**
- * Get the next continuation or similar special sibling (assuming
+ * Get the next continuation or similar ib-split sibling (assuming
  * block/inline alternation), conditionally on it having the same style.
  *
  * Since this is used when deciding to copy the new style context, it
@@ -2202,7 +2207,7 @@ ElementRestyler::CaptureChange(nsStyleContext* aOldContext,
 /**
  * Recompute style for mFrame (which should not have a prev continuation
  * with the same style), all of its next continuations with the same
- * style, and all special siblings of the same type (either block or
+ * style, and all ib-split siblings of the same type (either block or
  * inline, skipping the intermediates of the other type) and accumulate
  * changes into mChangeList given that mHintsHandled is already accumulated
  * for an ancestor.
@@ -2840,7 +2845,7 @@ GetNextBlockInInlineSibling(FramePropertyTable* aPropTable, nsIFrame* aFrame)
 {
   NS_ASSERTION(!aFrame->GetPrevContinuation(),
                "must start with the first continuation");
-  // Might we have special siblings?
+  // Might we have ib-split siblings?
   if (!(aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) {
     // nothing more to do here
     return nullptr;
@@ -2868,7 +2873,7 @@ RestyleManager::ComputeStyleChangeFor(nsIFrame*          aFrame,
                "must start with the first continuation");
 
   // We want to start with this frame and walk all its next-in-flows,
-  // as well as all its special siblings and their next-in-flows,
+  // as well as all its ib-split siblings and their next-in-flows,
   // reresolving style on all the frames we encounter in this walk that
   // we didn't reach already.  In the normal case, this will mean only
   // restyling the first two block-in-inline splits and no
@@ -2890,7 +2895,7 @@ RestyleManager::ComputeStyleChangeFor(nsIFrame*          aFrame,
   nsTArray<nsIContent*> visibleKidsOfHiddenElement;
   for (nsIFrame* ibSibling = aFrame; ibSibling;
        ibSibling = GetNextBlockInInlineSibling(propTable, ibSibling)) {
-    // Outer loop over special siblings
+    // Outer loop over ib-split siblings
     for (nsIFrame* cont = ibSibling; cont; cont = cont->GetNextContinuation()) {
       if (GetPrevContinuationWithSameStyle(cont)) {
         // We already handled this element when dealing with its earlier
@@ -2908,7 +2913,7 @@ RestyleManager::ComputeStyleChangeFor(nsIFrame*          aFrame,
 
       if (restyler.HintsHandledForFrame() & nsChangeHint_ReconstructFrame) {
         // If it's going to cause a framechange, then don't bother
-        // with the continuations or special siblings since they'll be
+        // with the continuations or ib-split siblings since they'll be
         // clobbered by the frame reconstruct anyway.
         NS_ASSERTION(!cont->GetPrevContinuation(),
                      "continuing frame had more severe impact than first-in-flow");
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 254a7ec69624..678a0c99c2cf 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -420,7 +420,7 @@ static nsIFrame* GetIBSplitSibling(nsIFrame* aFrame)
 {
   NS_PRECONDITION(IsFramePartOfIBSplit(aFrame), "Shouldn't call this");
 
-  // We only store the "special sibling" annotation with the first
+  // We only store the "ib-split sibling" annotation with the first
   // frame in the continuation chain. Walk back to find that frame now.
   return static_cast<nsIFrame*>
     (aFrame->FirstContinuation()->
@@ -431,7 +431,7 @@ static nsIFrame* GetIBSplitPrevSibling(nsIFrame* aFrame)
 {
   NS_PRECONDITION(IsFramePartOfIBSplit(aFrame), "Shouldn't call this");
 
-  // We only store the "special sibling" annotation with the first
+  // We only store the ib-split sibling annotation with the first
   // frame in the continuation chain. Walk back to find that frame now.  
   return static_cast<nsIFrame*>
     (aFrame->FirstContinuation()->
@@ -462,20 +462,20 @@ SetFrameIsIBSplit(nsIFrame* aFrame, nsIFrame* aIBSplitSibling)
 
   // We should be the only continuation
   NS_ASSERTION(!aFrame->GetPrevContinuation(),
-               "assigning special sibling to other than first continuation!");
+               "assigning ib-split sibling to other than first continuation!");
   NS_ASSERTION(!aFrame->GetNextContinuation() ||
                IsFramePartOfIBSplit(aFrame->GetNextContinuation()),
-               "should have no non-special continuations here");
+               "should have no non-ib-split continuations here");
 
-  // Mark the frame as "special".
+  // Mark the frame as ib-split.
   aFrame->AddStateBits(NS_FRAME_PART_OF_IBSPLIT);
 
   if (aIBSplitSibling) {
     NS_ASSERTION(!aIBSplitSibling->GetPrevContinuation(),
                  "assigning something other than the first continuation as the "
-                 "special sibling");
+                 "ib-split sibling");
 
-    // Store the "special sibling" (if we were given one) with the
+    // Store the ib-split sibling (if we were given one) with the
     // first frame in the flow.
     FramePropertyTable* props = aFrame->PresContext()->PropertyTable();
     props->Set(aFrame, nsIFrame::IBSplitSibling(), aIBSplitSibling);
@@ -499,9 +499,9 @@ GetIBContainingBlockFor(nsIFrame* aFrame)
       return aFrame;
     }
 
-    // Note that we ignore non-special frames which have a pseudo on their
+    // Note that we ignore non-ib-split frames which have a pseudo on their
     // style context -- they're not the frames we're looking for!  In
-    // particular, they may be hiding a real parent that _is_ special.
+    // particular, they may be hiding a real parent that _is_ in an ib-split.
     if (!IsFramePartOfIBSplit(parentFrame) &&
         !parentFrame->StyleContext()->GetPseudo())
       break;
@@ -510,7 +510,8 @@ GetIBContainingBlockFor(nsIFrame* aFrame)
   } while (1);
  
   // post-conditions
-  NS_ASSERTION(parentFrame, "no normal ancestor found for special frame in GetIBContainingBlockFor");
+  NS_ASSERTION(parentFrame, "no normal ancestor found for ib-split frame "
+                            "in GetIBContainingBlockFor");
   NS_ASSERTION(parentFrame != aFrame, "parentFrame is actually the child frame - bogus reslt");
 
   return parentFrame;
@@ -5743,7 +5744,7 @@ AdjustAppendParentForAfterContent(nsPresContext* aPresContext,
     // empty.  Since we have no ::after pseudo-element, we do in fact want to be
     // appending to that last part, so advance to it if needed.  Note that here
     // aParentFrame is the result of a GetLastIBSplitSibling call, so must be
-    // either the last or next to last special sibling.
+    // either the last or next to last ib-split sibling.
     nsIFrame* trailingInline = GetIBSplitSibling(aParentFrame);
     if (trailingInline) {
       aParentFrame = trailingInline;
@@ -5751,7 +5752,7 @@ AdjustAppendParentForAfterContent(nsPresContext* aPresContext,
 
     // Always make sure to look at the last continuation of the frame
     // for the {ib} case, even if that continuation is empty.  We
-    // don't do this for the non-special-frame case, since in the
+    // don't do this for the non-ib-split-frame case, since in the
     // other cases appending to the last nonempty continuation is fine
     // and in fact not doing that can confuse code that doesn't know
     // to pull kids from continuations other than its next one.
@@ -5811,7 +5812,7 @@ nsCSSFrameConstructor::AppendFramesToParent(nsFrameConstructorState&       aStat
   NS_PRECONDITION(!IsFramePartOfIBSplit(aParentFrame) ||
                   !GetIBSplitSibling(aParentFrame) ||
                   !GetIBSplitSibling(aParentFrame)->GetFirstPrincipalChild(),
-                  "aParentFrame has a special sibling with kids?");
+                  "aParentFrame has a ib-split sibling with kids?");
   NS_PRECONDITION(!aPrevSibling || aPrevSibling->GetParent() == aParentFrame,
                   "Parent and prevsibling don't match");
 
@@ -6008,7 +6009,7 @@ nsCSSFrameConstructor::FindFrameForContentSibling(nsIContent* aContent,
   NS_ASSERTION(!sibling->GetPrevContinuation(), "How did that happen?");
 
   if (aPrevSibling) {
-    // The frame may be a special frame (a split inline frame that
+    // The frame may be a ib-split frame (a split inline frame that
     // contains a block).  Get the last part of that split.
     if (IsFramePartOfIBSplit(sibling)) {
       sibling = GetLastIBSplitSibling(sibling, true);
@@ -6636,16 +6637,16 @@ nsCSSFrameConstructor::ContentAppended(nsIContent*     aContainer,
     return rv;
   }
 
-  // If the frame we are manipulating is a ``special'' frame (that is, one
+  // If the frame we are manipulating is a ib-split frame (that is, one
   // that's been created as a result of a block-in-inline situation) then we
-  // need to append to the last special sibling, not to the frame itself.
+  // need to append to the last ib-split sibling, not to the frame itself.
   bool parentIBSplit = IsFramePartOfIBSplit(parentFrame);
   if (parentIBSplit) {
 #ifdef DEBUG
     if (gNoisyContentUpdates) {
       printf("nsCSSFrameConstructor::ContentAppended: parentFrame=");
       nsFrame::ListTag(stdout, parentFrame);
-      printf(" is special\n");
+      printf(" is ib-split\n");
     }
 #endif
 
@@ -6725,7 +6726,7 @@ nsCSSFrameConstructor::ContentAppended(nsIContent*     aContainer,
   nsIFrame* prevSibling = ::FindAppendPrevSibling(parentFrame, parentAfterFrame);
 
   // Perform special check for diddling around with the frames in
-  // a special inline frame.
+  // a ib-split inline frame.
   // If we're appending before :after content, then we're not really
   // appending, so let WipeContainingBlock know that.
   LAYOUT_PHASE_TEMP_EXIT();
@@ -7292,7 +7293,7 @@ nsCSSFrameConstructor::ContentRangeInserted(nsIContent*            aContainer,
   // (bug 341858).
   // This can affect our prevSibling and isAppend, but should not have any
   // effect on the WipeContainingBlock above, since this should only happen
-  // when neither parent is a special frame and should not affect whitespace
+  // when neither parent is a ib-split frame and should not affect whitespace
   // handling inside table-related frames (and in fact, can only happen when
   // one of the parents is an outer table and one is an inner table or when the
   // parent is a fieldset or fieldset content frame).  So it won't affect the
@@ -7310,7 +7311,7 @@ nsCSSFrameConstructor::ContentRangeInserted(nsIContent*            aContainer,
     nsIFrame* frame2 = prevSibling->GetParent();
     NS_ASSERTION(!IsFramePartOfIBSplit(frame1) &&
                  !IsFramePartOfIBSplit(frame2),
-                 "Neither should be special");
+                 "Neither should be ib-split");
     NS_ASSERTION((frame1->GetType() == nsGkAtoms::tableFrame &&
                   frame2->GetType() == nsGkAtoms::tableOuterFrame) ||
                  (frame1->GetType() == nsGkAtoms::tableOuterFrame &&
@@ -8430,7 +8431,7 @@ nsCSSFrameConstructor::MaybeRecreateContainerForFrameRemoval(nsIFrame* aFrame,
       printf("nsCSSFrameConstructor::MaybeRecreateContainerForFrameRemoval: "
              "frame=");
       nsFrame::ListTag(stdout, aFrame);
-      printf(" is special\n");
+      printf(" is ib-split\n");
     }
 #endif
 
@@ -8564,7 +8565,7 @@ nsCSSFrameConstructor::MaybeRecreateContainerForFrameRemoval(nsIFrame* aFrame,
   }
 
   // We might still need to reconstruct things if the parent of inFlowFrame is
-  // special, since in that case the removal of aFrame might affect the
+  // ib-split, since in that case the removal of aFrame might affect the
   // splitting of its parent.
   if (!IsFramePartOfIBSplit(parent)) {
     return false;
@@ -8591,7 +8592,7 @@ nsCSSFrameConstructor::MaybeRecreateContainerForFrameRemoval(nsIFrame* aFrame,
     printf("nsCSSFrameConstructor::MaybeRecreateContainerForFrameRemoval: "
            "frame=");
     nsFrame::ListTag(stdout, parent);
-    printf(" is special\n");
+    printf(" is ib-split\n");
   }
 #endif
 
@@ -8612,7 +8613,7 @@ nsCSSFrameConstructor::RecreateFramesForContent(nsIContent* aContent,
   // frame tree for chrome (see bug 157322).
   NS_ENSURE_TRUE(aContent->GetDocument(), NS_ERROR_FAILURE);
 
-  // Is the frame `special'? If so, we need to reframe the containing
+  // Is the frame ib-split? If so, we need to reframe the containing
   // block *here*, rather than trying to remove and re-insert the
   // content (which would otherwise result in *two* nested reframe
   // containing block from ContentRemoved() and ContentInserted(),
@@ -10693,7 +10694,7 @@ nsCSSFrameConstructor::BuildInlineChildItems(nsFrameConstructorState& aState,
 
 // return whether it's ok to append (in the AppendFrames sense) to
 // aParentFrame if our nextSibling is aNextSibling.  aParentFrame must
-// be an {ib} special inline.
+// be an ib-split inline.
 static bool
 IsSafeToAppendToIBSplitInline(nsIFrame* aParentFrame, nsIFrame* aNextSibling)
 {
@@ -10701,7 +10702,7 @@ IsSafeToAppendToIBSplitInline(nsIFrame* aParentFrame, nsIFrame* aNextSibling)
                   "Must have an inline parent here");
   do {
     NS_ASSERTION(IsFramePartOfIBSplit(aParentFrame),
-                 "How is this not special?");
+                 "How is this not part of an ib-split?");
     if (aNextSibling || aParentFrame->GetNextContinuation() ||
         GetIBSplitSibling(aParentFrame)) {
       return false;
@@ -10995,7 +10996,8 @@ nsCSSFrameConstructor::WipeContainingBlock(nsFrameConstructorState& aState,
       break;
     }
 
-    // Now we know we have a block parent.  If it's not special, we're all set.
+    // Now we know we have a block parent.  If it's not part of an
+    // ib-split, we're all set.
     if (!IsFramePartOfIBSplit(aFrame)) {
       return false;
     }
@@ -11017,7 +11019,7 @@ nsCSSFrameConstructor::WipeContainingBlock(nsFrameConstructorState& aState,
   
   // To find the right block to reframe, just walk up the tree until we find a
   // frame that is:
-  // 1)  Not part of an IB split (not special)
+  // 1)  Not part of an IB split
   // 2)  Not a pseudo-frame
   // 3)  Not an inline frame
   // We're guaranteed to find one, since nsStyleContext::ApplyStyleFixups
@@ -11032,8 +11034,8 @@ nsCSSFrameConstructor::WipeContainingBlock(nsFrameConstructorState& aState,
          aContainingBlock->StyleContext()->GetPseudo()) {
     aContainingBlock = aContainingBlock->GetParent();
     NS_ASSERTION(aContainingBlock,
-                 "Must have non-inline, non-special, non-pseudo frame as root "
-                 "(or child of root, for a table root)!");
+                 "Must have non-inline, non-ib-split, non-pseudo frame as "
+                 "root (or child of root, for a table root)!");
   }
 
   // Tell parent of the containing block to reformulate the
@@ -11058,7 +11060,7 @@ nsCSSFrameConstructor::ReframeContainingBlock(nsIFrame* aFrame)
 #ifdef DEBUG
   // ReframeContainingBlock is a NASTY routine, it causes terrible performance problems
   // so I want to see when it is happening!  Unfortunately, it is happening way to often because
-  // so much content on the web causes 'special' block-in-inline frame situations and we handle them
+  // so much content on the web causes block-in-inline frame situations and we handle them
   // very poorly
   if (gNoisyContentUpdates) {
     printf("nsCSSFrameConstructor::ReframeContainingBlock frame=%p\n",
diff --git a/layout/base/nsCSSFrameConstructor.h b/layout/base/nsCSSFrameConstructor.h
index d738aa18c4ea..771251eb43da 100644
--- a/layout/base/nsCSSFrameConstructor.h
+++ b/layout/base/nsCSSFrameConstructor.h
@@ -369,7 +369,7 @@ private:
                                   FrameConstructionItemList& aItems);
 
   // This method can change aFrameList: it can chop off the beginning and put
-  // it in aParentFrame while putting the remainder into a special sibling of
+  // it in aParentFrame while putting the remainder into a ib-split sibling of
   // aParentFrame.  aPrevSibling must be the frame after which aFrameList is to
   // be placed on aParentFrame's principal child list.  It may be null if
   // aFrameList is being added at the beginning of the child list.
diff --git a/layout/base/nsCSSRendering.cpp b/layout/base/nsCSSRendering.cpp
index 13bd86bc0a54..68f6a08041d3 100644
--- a/layout/base/nsCSSRendering.cpp
+++ b/layout/base/nsCSSRendering.cpp
@@ -99,7 +99,7 @@ struct InlineBackgroundData
       nscoord curOffset = aFrame->GetOffsetTo(mBlockFrame).x;
 
       // No need to use our GetPrevContinuation/GetNextContinuation methods
-      // here, since ib special siblings are certainly not on the same line.
+      // here, since ib-split siblings are certainly not on the same line.
 
       nsIFrame* inlineFrame = aFrame->GetPrevContinuation();
       // If the continuation is fluid we know inlineFrame is not on the same line.
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index e124ed67a4e0..095353700e3c 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -2728,7 +2728,7 @@ nsLayoutUtils::GetNextContinuationOrIBSplitSibling(nsIFrame *aFrame)
     return result;
 
   if ((aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT) != 0) {
-    // We only store the "special sibling" annotation with the first
+    // We only store the ib-split sibling annotation with the first
     // frame in the continuation chain. Walk back to find that frame now.
     aFrame = aFrame->FirstContinuation();
 
diff --git a/layout/base/nsLayoutUtils.h b/layout/base/nsLayoutUtils.h
index b01099c8b0f4..45f60a814ca1 100644
--- a/layout/base/nsLayoutUtils.h
+++ b/layout/base/nsLayoutUtils.h
@@ -1011,13 +1011,14 @@ public:
   static nsIFrame* GetParentOrPlaceholderForCrossDoc(nsIFrame* aFrame);
 
   /**
-   * Get a frame's next-in-flow, or, if it doesn't have one, its special sibling.
+   * Get a frame's next-in-flow, or, if it doesn't have one, its
+   * block-in-inline-split sibling.
    */
   static nsIFrame*
   GetNextContinuationOrIBSplitSibling(nsIFrame *aFrame);
 
   /**
-   * Get the first frame in the continuation-plus-special-sibling chain
+   * Get the first frame in the continuation-plus-ib-split-sibling chain
    * containing aFrame.
    */
   static nsIFrame*
diff --git a/layout/generic/StickyScrollContainer.cpp b/layout/generic/StickyScrollContainer.cpp
index 59bb8b82a346..acb74f2cfc07 100644
--- a/layout/generic/StickyScrollContainer.cpp
+++ b/layout/generic/StickyScrollContainer.cpp
@@ -357,7 +357,7 @@ StickyScrollContainer::UpdatePositions(nsPoint aScrollPosition,
     nsIFrame* f = mFrames[i];
     if (!nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(f)) {
       // This frame was added in nsFrame::Init before we knew it wasn't
-      // the first special-sibling.
+      // the first ib-split-sibling.
       mFrames.RemoveElementAt(i);
       --i;
       continue;
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index bd64d2f2424b..728c822589da 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -500,7 +500,7 @@ nsFrame::Init(nsIContent*      aContent,
       !(mState & NS_FRAME_IS_NONDISPLAY) &&
       !disp->IsInnerTableStyle()) {
     // Note that we only add first continuations, but we really only
-    // want to add first continuation-or-special-siblings.  But since we
+    // want to add first continuation-or-ib-split-siblings.  But since we
     // don't yet know if we're a later part of a block-in-inline split,
     // we'll just add later members of a block-in-inline split here, and
     // then StickyScrollContainer will remove them later.
@@ -619,7 +619,7 @@ nsFrame::DestroyFrom(nsIFrame* aDestructRoot)
     }
   }
 
-  // If we have any IB split special siblings, clear their references to us.
+  // If we have any IB split siblings, clear their references to us.
   // (Note: This has to happen before we call shell->NotifyDestroyingFrame,
   // because that clears our Properties() table.)
   if (mState & NS_FRAME_PART_OF_IBSPLIT) {
@@ -6021,9 +6021,10 @@ FindBlockFrameOrBR(nsIFrame* aFrame, nsDirection aDirection)
     return result;
   
   // Check the frame itself
-  // Fall through "special" block frames because their mContent is the content
-  // of the inline frames they were created from. The first/last child of
-  // such frames is the real block frame we're looking for.
+  // Fall through block-in-inline split frames because their mContent is
+  // the content of the inline frames they were created from. The
+  // first/last child of such frames is the real block frame we're
+  // looking for.
   if ((nsLayoutUtils::GetAsBlock(aFrame) &&
        !(aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT)) ||
       aFrame->GetType() == nsGkAtoms::brFrame) {
@@ -7162,10 +7163,11 @@ nsFrame::ConsiderChildOverflow(nsOverflowAreas& aOverflowAreas,
 }
 
 /**
- * This function takes a "special" frame and _if_ that frame is an anonymous
- * block created by an ib split it returns the block's preceding inline.  This
- * is needed because the split inline's style context is the parent of the
- * anonymous block's style context.
+ * This function takes a frame that is part of a block-in-inline split,
+ * and _if_ that frame is an anonymous block created by an ib split it
+ * returns the block's preceding inline.  This is needed because the
+ * split inline's style context is the parent of the anonymous block's
+ * style context.
  *
  * If aFrame is not an anonymous block, null is returned.
  */
@@ -7174,7 +7176,7 @@ GetIBSplitSiblingForAnonymousBlock(const nsIFrame* aFrame)
 {
   NS_PRECONDITION(aFrame, "Must have a non-null frame!");
   NS_ASSERTION(aFrame->GetStateBits() & NS_FRAME_PART_OF_IBSPLIT,
-               "GetIBSplitSibling should not be called on a non-special frame");
+               "GetIBSplitSibling should only be called on ib-split frames");
 
   nsIAtom* type = aFrame->StyleContext()->GetPseudo();
   if (type != nsCSSAnonBoxes::mozAnonymousBlock &&
diff --git a/layout/generic/nsFrameStateBits.h b/layout/generic/nsFrameStateBits.h
index 58559e1630e7..3597c7809c5e 100644
--- a/layout/generic/nsFrameStateBits.h
+++ b/layout/generic/nsFrameStateBits.h
@@ -135,9 +135,8 @@ FRAME_STATE_BIT(Generic, 13, NS_FRAME_HAS_VIEW)
 // If this bit is set, the frame was created from anonymous content.
 FRAME_STATE_BIT(Generic, 14, NS_FRAME_INDEPENDENT_SELECTION)
 
-// If this bit is set, the frame is "special" (lame term, I know),
-// which means that it is part of the mangled frame hierarchy that
-// results when an inline has been split because of a nested block.
+// If this bit is set, the frame is part of the mangled frame hierarchy
+// that results when an inline has been split because of a nested block.
 // See the comments in nsCSSFrameConstructor::ConstructInline for
 // more details.
 FRAME_STATE_BIT(Generic, 15, NS_FRAME_PART_OF_IBSPLIT)
diff --git a/layout/generic/nsInlineFrame.cpp b/layout/generic/nsInlineFrame.cpp
index 73b0fa0dcf7a..da2b24ba6477 100644
--- a/layout/generic/nsInlineFrame.cpp
+++ b/layout/generic/nsInlineFrame.cpp
@@ -124,8 +124,8 @@ nsInlineFrame::IsSelfEmpty()
         haveStart = haveRight;
         haveEnd = haveLeft;
       }
-      // For special frames, ignore things we know we'll skip in GetSkipSides.
-      // XXXbz should we be doing this for non-special frames too, in a more
+      // For ib-split frames, ignore things we know we'll skip in GetSkipSides.
+      // XXXbz should we be doing this for non-ib-split frames too, in a more
       // general way?
 
       // Get the first continuation eagerly, as a performance optimization, to
diff --git a/layout/generic/nsLineLayout.cpp b/layout/generic/nsLineLayout.cpp
index cdb596e763b8..39e0750a36cb 100644
--- a/layout/generic/nsLineLayout.cpp
+++ b/layout/generic/nsLineLayout.cpp
@@ -1069,9 +1069,10 @@ nsLineLayout::ApplyStartMargin(PerFrameData* pfd,
 
   // Only apply start-margin on the first-in flow for inline frames,
   // and make sure to not apply it to any inline other than the first
-  // in an ib split.  Note that the ib special sibling annotations
-  // only live on the first continuation, but we don't want to apply
-  // the start margin for later continuations anyway.
+  // in an ib split.  Note that the ib sibling (block-in-inline
+  // sibling) annotations only live on the first continuation, but we
+  // don't want to apply the start margin for later continuations
+  // anyway.
   if (pfd->mFrame->GetPrevContinuation() ||
       pfd->mFrame->FrameIsNonFirstInIBSplit()) {
     // Zero this out so that when we compute the max-element-width of
diff --git a/layout/style/nsStyleContext.h b/layout/style/nsStyleContext.h
index f6141aba26f9..34c0b32d5ebc 100644
--- a/layout/style/nsStyleContext.h
+++ b/layout/style/nsStyleContext.h
@@ -274,7 +274,7 @@ public:
    * requested.)
    *
    * This method returns a change hint (see nsChangeHint.h).  All change
-   * hints apply to the frame and its later continuations or special
+   * hints apply to the frame and its later continuations or ib-split
    * siblings.  Most (all of those except the "NotHandledForDescendants"
    * hints) also apply to all descendants.  The caller must pass in any
    * non-inherited hints that resulted from the parent style context's
diff --git a/layout/svg/nsSVGIntegrationUtils.cpp b/layout/svg/nsSVGIntegrationUtils.cpp
index dc109f57789b..4383622f62d1 100644
--- a/layout/svg/nsSVGIntegrationUtils.cpp
+++ b/layout/svg/nsSVGIntegrationUtils.cpp
@@ -76,14 +76,14 @@ private:
       return *r;
     }
     // Despite the fact that we're invoked for frames with SVG effects applied,
-    // we can actually get here. All continuations and special siblings of a
+    // we can actually get here. All continuations and IB split siblings of a
     // frame with SVG effects applied will have the PreEffectsBBoxProperty
     // property set on them. Therefore, the frames that are passed to us will
     // always have that property set...well, with one exception. If the frames
     // for an element with SVG effects applied have been subject to an "IB
     // split", then the block frame(s) that caused the split will have been
     // wrapped in anonymous, inline-block, nsBlockFrames of pseudo-type
-    // nsCSSAnonBoxes::mozAnonymousBlock. These "special sibling" anonymous
+    // nsCSSAnonBoxes::mozAnonymousBlock. These "IB split sibling" anonymous
     // blocks will have the PreEffectsBBoxProperty property set on them, but
     // they will never be passed to us. Instead, we'll be passed the block
     // children that they wrap, which don't have the PreEffectsBBoxProperty