diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/java.xml/share/classes/com/sun/org/apache/xpath/internal/axes/SubContextList.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.xml/share/classes/com/sun/org/apache/xpath/internal/axes/SubContextList.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,53 @@
+/*
+ * reserved comment block
+ * DO NOT REMOVE OR ALTER!
+ */
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.sun.org.apache.xpath.internal.axes;
+
+import com.sun.org.apache.xpath.internal.XPathContext;
+
+/**
+ * A class that implements this interface is a sub context node list, meaning it
+ * is a node list for a location path step for a predicate.
+ * @xsl.usage advanced
+ */
+public interface SubContextList
+{
+
+  /**
+   * Get the number of nodes in the node list, which, in the XSLT 1 based
+   * counting system, is the last index position.
+   *
+   *
+   * @param xctxt The XPath runtime context.
+   *
+   * @return the number of nodes in the node list.
+   */
+  public int getLastPos(XPathContext xctxt);
+
+  /**
+   * Get the current sub-context position.
+   *
+   * @param xctxt The XPath runtime context.
+   *
+   * @return The position of the current node in the list.
+   */
+  public int getProximityPosition(XPathContext xctxt);
+}