Index: src/java/org/apache/fop/datatypes/LengthBase.java
===================================================================
--- src/java/org/apache/fop/datatypes/LengthBase.java	(revision 517354)
+++ src/java/org/apache/fop/datatypes/LengthBase.java	(working copy)
@@ -47,21 +47,23 @@
     /** constant for a containing refarea percent-based length */
     public static final int CONTAINING_REFAREA_WIDTH = 4;
     /** constant for a containing block percent-based length */
-    public static final int CONTAINING_BLOCK_WIDTH = 5;
+    public static final int CONTAINING_REFAREA_HEIGHT = 5;
     /** constant for a containing block percent-based length */
-    public static final int CONTAINING_BLOCK_HEIGHT = 6;
+    public static final int CONTAINING_BLOCK_WIDTH = 6;
+    /** constant for a containing block percent-based length */
+    public static final int CONTAINING_BLOCK_HEIGHT = 7;
     /** constant for a image intrinsic percent-based length */
-    public static final int IMAGE_INTRINSIC_WIDTH = 7;
+    public static final int IMAGE_INTRINSIC_WIDTH = 8;
     /** constant for a image intrinsic percent-based length */
-    public static final int IMAGE_INTRINSIC_HEIGHT = 8;
+    public static final int IMAGE_INTRINSIC_HEIGHT = 9;
     /** constant for a image background position horizontal percent-based length */
-    public static final int IMAGE_BACKGROUND_POSITION_HORIZONTAL = 9;
+    public static final int IMAGE_BACKGROUND_POSITION_HORIZONTAL = 10;
     /** constant for a image background position vertical percent-based length */
-    public static final int IMAGE_BACKGROUND_POSITION_VERTICAL = 10;
+    public static final int IMAGE_BACKGROUND_POSITION_VERTICAL = 11;
     /** constant for a table-unit-based length */
-    public static final int TABLE_UNITS = 11;
+    public static final int TABLE_UNITS = 12;
     /** constant for a alignment adjust percent-based length */
-    public static final int ALIGNMENT_ADJUST = 12;
+    public static final int ALIGNMENT_ADJUST = 13;
 
     /**
      * logging instance
Index: src/java/org/apache/fop/fo/FOPropertyMapping.java
===================================================================
--- src/java/org/apache/fop/fo/FOPropertyMapping.java	(revision 517354)
+++ src/java/org/apache/fop/fo/FOPropertyMapping.java	(working copy)
@@ -410,6 +410,7 @@
         l.setInherited(false);
         l.addEnum("auto", getEnumProperty(EN_AUTO, "AUTO"));
         l.setDefault("auto");
+        l.setPercentBase(LengthBase.CONTAINING_REFAREA_HEIGHT);
         addPropertyMaker("top", l);
 
         // right
@@ -417,6 +418,7 @@
         l.setInherited(false);
         l.addEnum("auto", getEnumProperty(EN_AUTO, "AUTO"));
         l.setDefault("auto");
+        l.setPercentBase(LengthBase.CONTAINING_REFAREA_WIDTH);
         addPropertyMaker("right", l);
 
         // bottom
@@ -424,6 +426,7 @@
         l.setInherited(false);
         l.addEnum("auto", getEnumProperty(EN_AUTO, "AUTO"));
         l.setDefault("auto");
+        l.setPercentBase(LengthBase.CONTAINING_REFAREA_HEIGHT);
         addPropertyMaker("bottom", l);
 
         // left
@@ -431,6 +434,7 @@
         l.setInherited(false);
         l.addEnum("auto", getEnumProperty(EN_AUTO, "AUTO"));
         l.setDefault("auto");
+        l.setPercentBase(LengthBase.CONTAINING_REFAREA_WIDTH);
         addPropertyMaker("left", l);
     }
 
Index: src/java/org/apache/fop/layoutmgr/AbstractBaseLayoutManager.java
===================================================================
--- src/java/org/apache/fop/layoutmgr/AbstractBaseLayoutManager.java	(revision 517354)
+++ src/java/org/apache/fop/layoutmgr/AbstractBaseLayoutManager.java	(working copy)
@@ -81,6 +81,8 @@
                 return getParentAreaIPD();
             case LengthBase.CONTAINING_REFAREA_WIDTH:
                 return getReferenceAreaIPD();
+            case LengthBase.CONTAINING_REFAREA_HEIGHT:
+                return getReferenceAreaBPD();
             default:
                 log.error(new Exception("Unknown base type for LengthBase:" + lengthBase));
                 return 0;