Moving steps prose

dom.bs

@@ -2866,7 +2866,12 @@ before a <var>child</var>, with an optional <i>suppress observers flag</i>, run
 <p><a lt="Other applicable specifications">Specifications</a> may define <dfn export
 id=concept-moving-steps-ext>moving steps</dfn> for all or some <a for=/>nodes</a>. The algorithm is
 passed a <a for=/>node</a> <var ignore>movedNode</var>, and a <a for=/>node</a>-or-null <var
-ignore>oldParent</var> as indicated in the <a for=/>move</a> algorithm below.
+ignore>oldParent</var> as indicated in the <a for=/>move</a> algorithm below. Like the <span
+data-x="concept-insertion-steps-ext">insertion steps</span>, these steps must not modify the
+<a>node tree</a> that <var>insertedNode</var> <a>participates</a> in, create
+<a for=/>browsing contexts</a>, <a lt="fire an event">fire events</a>, or otherwise execute
+JavaScript. These steps may queue tasks to do these things asynchronously, however.
+
 
 <p>To <dfn export id=concept-node-move>move</dfn> a <var>node</var> into a <var>parent</var> before
 a <var>child</var>, run these steps: