diff --git a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9c/FCDotPIE9CDash04.java b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9c/FCDotPIE9CDash04.java
index f973550..d14bf45 100644
--- a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9c/FCDotPIE9CDash04.java
+++ b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9c/FCDotPIE9CDash04.java
@@ -37,10 +37,10 @@ import org.x4o.fc18.cake2.zero33.FCDotCDC1604DashP6;
  */
 public enum FCDotPIE9CDash04 implements FourCornerDotCollePie9 {
 	
-	NXX_01(' '),
-	NXX_02(' '),
-	NXX_03('∎'),
-	NXX_04(' '),
+	NXX_01('⍎'), // from APL
+	NXX_02('⍕'), // from APL
+	NXX_03('⌿'), // from APL
+	NXX_04('⍀'), // from APL
 	;
 	private final List<Integer> codePointDisplay;
 	
diff --git a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash16.java b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash16.java
index 53bd9da..33e3cc7 100644
--- a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash16.java
+++ b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash16.java
@@ -37,22 +37,22 @@ import org.x4o.fc18.cake2.zero33.FCDotCDC1604DashP6;
  */
 public enum FCDotPIE9DDash16 implements FourCornerDotCollePie9 {
 	
-	NXX_01(' '),
-	NXX_02(' '),
-	NXX_03(' '),
-	NXX_04(' '),
-	NXX_05(' '),
-	NXX_06(' '),
-	NXX_07(' '),
-	NXX_08(' '),
-	NXX_09(' '),
-	NXX_10(' '),
-	NXX_11(' '),
-	NXX_12(' '),
-	NXX_13(' '),
-	NXX_14(' '),
-	NXX_15(' '),
-	NXX_16(' '),
+	NXX_01('⏴'),
+	NXX_02('⏵'),
+	NXX_03('⏶'),
+	NXX_04('⏷'),
+	NXX_05('⏸'),
+	NXX_06('⏹'),
+	NXX_07('⏺'),
+	NXX_08('⏭'),
+	NXX_09('⏮'),
+	NXX_10('⏯'),
+	NXX_11('⏏'),
+	NXX_12('⏻'),
+	NXX_13('⏼'),
+	NXX_14('⏽'),
+	NXX_15('⏾'),
+	NXX_16('⏎'),
 	;
 	private final List<Integer> codePointDisplay;
 	
diff --git a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash17.java b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash17.java
index 108a804..7142151 100644
--- a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash17.java
+++ b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/pie9d/FCDotPIE9DDash17.java
@@ -37,23 +37,23 @@ import org.x4o.fc18.cake2.zero33.FCDotCDC1604DashP6;
  */
 public enum FCDotPIE9DDash17 implements FourCornerDotCollePie9 {
 	
-	NXX_01(' '),
-	NXX_02(' '),
-	NXX_03(' '),
-	NXX_04(' '),
-	NXX_05(' '),
-	NXX_06(' '),
-	NXX_07(' '),
-	NXX_08(' '),
-	NXX_09(' '),
-	NXX_10(' '),
-	NXX_11(' '),
-	NXX_12(' '),
-	NXX_13(' '),
-	NXX_14(' '),
-	NXX_15(' '),
-	NXX_16(' '),
-	NXX_17(' '),
+	NXX_01('⋆'),
+	NXX_02('⍣'), // from APL
+	NXX_03('∘'), // from APL
+	NXX_04('⍤'), // from APL
+	NXX_05('∼'),
+	NXX_06('⍨'), // from APL
+	NXX_07('∙'),
+	NXX_08('⌖'),
+	NXX_09('⋅'),
+	NXX_10('⋇'),
+	NXX_11('⍘'),
+	NXX_12('⍪'), // from APL
+	NXX_13('⋄'), // from APL
+	NXX_14('⍚'),
+	NXX_15('⍛'),
+	NXX_16('⍜'),
+	NXX_17('∎'),
 	;
 	private final List<Integer> codePointDisplay;
 	
diff --git a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7A.java b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7A.java
index f0a0d81..8748f15 100644
--- a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7A.java
+++ b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7A.java
@@ -75,17 +75,17 @@ public enum FCDotAPL0127DashP7A implements FourCornerDotColleZero33 {
 	// === 8 mirrors
 	
 	/// SL190000
-	DOWN_TACK_JOT('⍎'),
+	__DOWN_TACK_JOT(' '),
 	/// SL200000
-	UP_TACK_JOT('⍕'),
+	__UP_TACK_JOT(' '),
 	/// SL150000
-	SLASH_BAR('⌿'),
+	__SLASH_BAR(' '),
 	/// SL160000
-	SLOPE_BAR('⍀'),
+	__SLOPE_BAR(' '),
 	/// SL010000 
-	UP_STILE('⌈'),
+	__UP_STILE(' '),
 	/// SL020000
-	DOWN_STILE('⌊'),
+	__DOWN_STILE(' '),
 	/// SL030000 (used in GNU GPL)
 	__DEL(' '),
 	/// SL060000 (used in GNU GPL)
diff --git a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7B.java b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7B.java
index f38cfb3..1abadf1 100644
--- a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7B.java
+++ b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7B.java
@@ -38,11 +38,11 @@ public enum FCDotAPL0127DashP7B implements FourCornerDotColleZero33 {
 	/// NEW from dynlog APL
 	__CIRCLE_DOT_XL(' '),
 	/// NEW from dynlog APL
-	CIRLCE_DOT('⍤'),
+	__CIRLCE_DOT(' '),
 	/// SL250000
-	JOT('∘'),
+	__JOT(' '),
 	/// NEW from dynlog APL
-	STAR_DOT('⍣'),
+	__STAR_DOT(' '),
 	
 	// === ALGOL_60 <arithmetic operator> ::= + | - | × | / | ÷ | ↑
 	
@@ -94,7 +94,7 @@ public enum FCDotAPL0127DashP7B implements FourCornerDotColleZero33 {
 	/// SL240000
 	IBEAM_TACK('⌶'),
 	/// NEW from DYNA
-	DOTTED_TILDE('⍨'),
+	__DOTTED_TILDE(' '),
 	/// SL450000
 	DIAERESIS('¨'),
 	// SL870000
diff --git a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7C.java b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7C.java
index 01741c4..115596a 100644
--- a/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7C.java
+++ b/nx01-x4o-fc18/src/main/java/org/x4o/fc18/cake2/zero33/FCDotAPL0127DashP7C.java
@@ -44,7 +44,7 @@ public enum FCDotAPL0127DashP7C implements FourCornerDotColleZero33 {
 	/// SL740000
 	__RHO(' '),
 	/// NEW from dynlog APL
-	MINUS_COMMA('⍪'),
+	__MINUS_COMMA(' '),
 	
 	/// --------- Left over from IBM APL
 	
@@ -71,7 +71,7 @@ public enum FCDotAPL0127DashP7C implements FourCornerDotColleZero33 {
 	// SL330000
 	__DELTA_UNDERBAR(' '), // GNU APL: user var: starts (A-Z) or one of the 3 characters _, ∆ , or ⍙
 	/// SL370000
-	LESS_GREATER('⋄'), // each stmt
+	__LESS_GREATER(' '), // each stmt
 	/// SL480000
 	__CIRCLE_PLUS(' '), // group
 	/// SL490000
diff --git a/nx01-x4o-fc18/src/test/java/org/x4o/fc18/cake2/pie9/FCDotPIE9Test.java b/nx01-x4o-fc18/src/test/java/org/x4o/fc18/cake2/pie9/FCDotPIE9Test.java
new file mode 100644
index 0000000..06e6cd6
--- /dev/null
+++ b/nx01-x4o-fc18/src/test/java/org/x4o/fc18/cake2/pie9/FCDotPIE9Test.java
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2004-2014, Willem Cazander
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided
+ * that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this list of conditions and the
+ *   following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and
+ *   the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+ * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.x4o.fc18.cake2.pie9;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.x4o.fc18.FourCornerUnicodeDisplay;
+import org.x4o.fc18.cake2.FourCornerDotCake;
+
+public class FCDotPIE9Test {
+	
+	String pieChars;
+	
+	public FCDotPIE9Test() {
+		int pieStart = FourCornerDotCake.FC_PIE9C_01.getStart();
+		int pieStop = FourCornerDotCake.FC_PIE9D_27.getStop();
+		List<Integer> cakePoints = new ArrayList<>();
+		for (int i = pieStart; i <= pieStop; i++) {
+			cakePoints.add(i);
+		}
+		FourCornerUnicodeDisplay disp = FourCornerUnicodeDisplay.text();
+		StringBuilder buf = new StringBuilder();
+		buf.append(disp.renderFromInt18(cakePoints));
+		pieChars = buf.toString();
+	}
+	
+	@Test
+	public void testUnusedMath() throws Exception {
+		int totalMissing = 0;
+		for (int i = 0x2200; i <= 0x22FF; i++) {
+			String mathChar = new StringBuilder().appendCodePoint(i).toString();
+			if (!pieChars.contains(mathChar)) {
+				totalMissing++;
+				//System.out.println(totalMissing + ":missing-math-chr: " + mathChar);
+			}
+		}
+		Assertions.assertTrue(totalMissing < 128, "To many math chars missing....");
+	}
+}