deploy.

App/wwwroot/HiAPI-docsite/api/Hi.NcParsers.html

@@ -217,11 +217,33 @@ radius entered against a tool-centre CAM path that expects wear only)
 shows up as an overcut instead of an alarm. The diagnostics built from
 this class exist to close that gap; they never change the path.</p>
 <p>
-Today the gate is meaningful on the XY plane (G17) only: both
-compensation engines build the perpendicular as <code>Z × axis</code>
-whatever plane is selected, so a G18/G19 region is neither compensated
-in its own plane nor checked here — the <code>planeNormalDir</code> parameters
-are ready for the day the engines pass the selected plane through.
+The gate works on the selected G17/G18/G19 plane: both engines pass
+the block's plane through <code>planeNormalDir</code>, and the in-plane
+projections below use it (neither engine checks a polar G12.1 block).
+Until 2026-09-11 both engines built the perpendicular as
+<code>Z × axis</code> whatever plane was selected, so a G18/G19 region was
+offset along its normal and could never be judged here.
+</p>
+</dd>
+    </dl>
+    <dl class="jumplist">
+      <dt><a class="xref" href="Hi.NcParsers.RadiusCompPlaneChange.html">RadiusCompPlaneChange</a></dt>
+      <dd><p>Classifies a plane selection (G17/G18/G19) that arrives while cutter
+radius compensation is still active — the case a real control refuses.
+Fanuc stops with alarm PS0037 CAN NOT CHANGE PLANE IN CRC, which covers
+both a plane code inside the compensation mode and a plane code sharing
+its block with the G40 that cancels it; Siemens and Heidenhain have
+equivalents. Neither engine can honour such a change: the corner between
+the two blocks is built from one block's running axis on the old plane
+and the other's on the new one, so the path around the change mixes two
+planes — and the block after it is offset on a plane the block before it
+never saw. The diagnostics built from this class exist to name that;
+they never change the path.</p>
+<p>
+The check is on the plane actually resolving differently from the
+previous block's, so a plane code that re-selects the plane already in
+force stays silent, as does the plane code on the block that starts the
+region (a control accepts that one — compensation is not active yet).
 </p>
 </dd>
     </dl>