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diff --git a/cpukit/include/rtems/score/chain.h b/cpukit/include/rtems/score/chain.h
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+++ b/cpukit/include/rtems/score/chain.h
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+/**
+ * @file
+ *
+ * @ingroup ScoreChain
+ *
+ * @brief Chain Handler API
+ */
+
+/*
+ *  Copyright (c) 2010 embedded brains GmbH.
+ *
+ *  COPYRIGHT (c) 1989-2006.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.org/license/LICENSE.
+ */
+
+#ifndef _RTEMS_SCORE_CHAIN_H
+#define _RTEMS_SCORE_CHAIN_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  @defgroup ScoreChain Chain Handler
+ *
+ *  @ingroup Score
+ *
+ *  The Chain Handler is used to manage sets of entities.  This handler
+ *  provides two data structures.  The Chain Node data structure is included
+ *  as the first part of every data structure that will be placed on
+ *  a chain.  The second data structure is Chain Control which is used
+ *  to manage a set of Chain Nodes.
+ */
+/**@{*/
+
+/**
+ *  @typedef Chain_Node
+ *
+ *  This type definition promotes the name for the Chain Node used by
+ *  all RTEMS code.  It is a separate type definition because a forward
+ *  reference is required to define it.  See @ref Chain_Node_struct for
+ *  detailed information.
+ */
+typedef struct Chain_Node_struct Chain_Node;
+
+/**
+ *  @struct Chain_Node_struct
+ *
+ *  This is used to manage each element (node) which is placed
+ *  on a chain.
+ *
+ *  @note Typically, a more complicated structure will use the
+ *        chain package.  The more complicated structure will
+ *        include a chain node as the first element in its
+ *        control structure.  It will then call the chain package
+ *        with a pointer to that node element.  The node pointer
+ *        and the higher level structure start at the same address
+ *        so the user can cast the pointers back and forth.
+ *
+ */
+struct Chain_Node_struct {
+  /** This points to the node after this one on this chain. */
+  Chain_Node *next;
+  /** This points to the node immediate prior to this one on this chain. */
+  Chain_Node *previous;
+};
+
+/**
+ *  @struct Chain_Control
+ *
+ * This is used to manage a chain.  A chain consists of a doubly
+ * linked list of zero or more nodes.
+ *
+ * @note This implementation does not require special checks for
+ *   manipulating the first and last elements on the chain.
+ *   To accomplish this the @a Chain_Control structure is
+ *   treated as two overlapping @ref Chain_Node structures.
+ */
+typedef union {
+  struct {
+    Chain_Node Node;
+    Chain_Node *fill;
+  } Head;
+
+  struct {
+    Chain_Node *fill;
+    Chain_Node Node;
+  } Tail;
+} Chain_Control;
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+/* end of include file */