diff --git a/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/SidedPlane.java b/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/SidedPlane.java
index 238933c3a84..61d561d421b 100755
--- a/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/SidedPlane.java
+++ b/lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/SidedPlane.java
@@ -234,12 +234,24 @@ public class SidedPlane extends Plane implements Membership {
     return sigNum == this.sigNum;
   }
 
+  /**
+   * Check whether a point is strictly within a plane.
+   * @param v is the point.
+   * @return true if within.
+   */
   public boolean strictlyWithin(final Vector v) {
     double evalResult = evaluate(v.x, v.y, v.z);
     double sigNum = Math.signum(evalResult);
     return sigNum == 0.0 || sigNum == this.sigNum;
   }
 
+  /**
+   * Check whether a point is strictly within a plane.
+   * @param x is the point x value.
+   * @param y is the point y value.
+   * @param z is the point z value.
+   * @return true if within.
+   */
   public boolean strictlyWithin(double x, double y, double z) {
     double evalResult = evaluate(x, y, z);
     double sigNum = Math.signum(evalResult);