msubsup-issue.md

@@ -33,3 +33,57 @@ Semantic Tree:
 </stree>
 
 ```
+
+Straightforward translation of the semantic tree into the MathML element,
+naturally ruins the msubsup element. Here's the semantically enriched MathML:
+```html
+<math>
+  <msubsup semantic-type="superscript" semantic-role="latinletter" semantic-id="4" semantic-children="3,2">
+    <mrow semantic-type="subscript" semantic-role="subsup" semantic-id="3" semantic-children="0,1" semantic-parent="4">
+      <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="0" semantic-parent="3">a</mi>
+      <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="1" semantic-parent="3">b</mi>
+    </mrow>
+    <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="2" semantic-parent="4">c</mi>
+  </msubsup>
+</math>
+
+```
+
+**Observe that this does not affect elements where msubsup has discernably been used as a layout element.** See, for example the following sum expression:
+
+```html
+<math>
+  <msubsup>
+    <mi>∑</mi>
+    <mi>b</mi>
+    <mi>c</mi>
+  </msubsup>
+</math>
+
+```
+
+Semantic Tree:
+```html
+<stree>
+  <limboth role="sum" id="3">
+    <children>
+      <largeop role="sum" id="0">∑</largeop>
+      <identifier role="latinletter" font="italic" id="1">b</identifier>
+      <identifier role="latinletter" font="italic" id="2">c</identifier>
+    </children>
+  </limboth>
+</stree>
+
+```
+
+Semantically enriched MathML:
+```html
+<math>
+  <msubsup semantic-type="limboth" semantic-role="sum" semantic-id="3" semantic-children="0,1,2">
+    <mi semantic-type="largeop" semantic-role="sum" semantic-id="0" semantic-parent="3">∑</mi>
+    <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="1" semantic-parent="3">b</mi>
+    <mi semantic-type="identifier" semantic-role="latinletter" semantic-id="2" semantic-parent="3">c</mi>
+  </msubsup>
+</math>
+
+```
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