diff --git a/core/src/main/java/hudson/RelativePath.java b/core/src/main/java/hudson/RelativePath.java
index 0beadad283..c5f562db3b 100644
--- a/core/src/main/java/hudson/RelativePath.java
+++ b/core/src/main/java/hudson/RelativePath.java
@@ -14,8 +14,23 @@ import static java.lang.annotation.RetentionPolicy.*;
  * nearby parameters that belong to different parents.
  *
  * <p>
- * Currently, "..", "../..", etc. are supported to indicate
- * parameters that belong to the ancestors.
+ * ".." refers
+ * to values in the parent object, and "foo" refers to the child
+ * object of the current object named "foo". They can be combined
+ * with '/' like path, such as "../foo/bar", "../..", and etc.
+ *
+ * <p>
+ * A good way to think about this is the file system structure.
+ * {@code @RelativePath} is like the dirname, and {@code QueryParameter}
+ * is like the basename. Together they form a relative path.
+ * And because of the structured form submissions,
+ * form elements are organized in a tree structure of JSON objects,
+ * which is akin to directories and files.
+ *
+ * <p>
+ * The relative path then points from the current input element
+ * (for which you are doing form validation, for example) to the target
+ * input element that you want to obtain the value.
  *
  * @author Kohsuke Kawaguchi
  * @since 1.376
diff --git a/war/src/main/webapp/scripts/hudson-behavior.js b/war/src/main/webapp/scripts/hudson-behavior.js
index c274df4eb7..834f3fe64e 100644
--- a/war/src/main/webapp/scripts/hudson-behavior.js
+++ b/war/src/main/webapp/scripts/hudson-behavior.js
@@ -144,6 +144,9 @@ var FormChecker = {
  * @param {string} name
  *      Name of the control to find. Can include "../../" etc in the prefix.
  *      See @RelativePath.
+ *
+ *      We assume that the name is normalized and doesn't contain any redundant component.
+ *      That is, ".." can only appear as prefix, and "foo/../bar" is not OK (because it can be reduced to "bar")
  */
 function findNearBy(e,name) {
     while (name.startsWith("../")) {
@@ -151,21 +154,33 @@ function findNearBy(e,name) {
         e = findFormParent(e,null,true);
     }
 
+    // name="foo/bar/zot"  -> prefixes=["bar","foo"] & name="zot"
+    var prefixes = name.split("/");
+    name = prefixes.pop();
+    prefixes = prefixes.reverse();
+
     // does 'e' itself match the criteria?
     // as some plugins use the field name as a parameter value, instead of 'value'
     var p = findFormItem(e,name,function(e,filter) {
-        if (filter(e))    return e;
-        return null;
+        return filter(e) ? e : null;
     });
-    if (p!=null)    return p;
+    if (p!=null && prefixes.length==0)    return p;
 
     var owner = findFormParent(e,null,true);
 
-    function locate(iterator,e) {
+    function locate(iterator,e) {// keep finding elements until we find the good match
         while (true) {
             e = iterator(e,name);
             if (e==null)    return null;
-            if (findFormParent(e,null,true)==owner)
+
+            // make sure this candidate element 'e' is in the right point in the hierarchy
+            var p = e;
+            for (var i=0; i<prefixes.length; i++) {
+                p = findFormParent(p,null,true);
+                if (p.getAttribute("name")!=prefixes[i])
+                    return null;
+            }
+            if (findFormParent(p,null,true)==owner)
                 return e;
         }
     }