diff --git a/MdePkg/Include/IndustryStandard/Acpi.h b/MdePkg/Include/IndustryStandard/Acpi.h
index ead115089d..4ce19e247d 100644
--- a/MdePkg/Include/IndustryStandard/Acpi.h
+++ b/MdePkg/Include/IndustryStandard/Acpi.h
@@ -2,7 +2,7 @@
   This file contains the latest ACPI definitions that are
   consumed by drivers that do not care about ACPI versions.
 
-  Copyright (c) 2006, Intel Corporation
+  Copyright (c) 2006 - 2008, Intel Corporation
   All rights reserved. This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -16,6 +16,6 @@
 #ifndef _ACPI_H_
 #define _ACPI_H_
 
-#include <IndustryStandard/Acpi3_0.h>
+#include <IndustryStandard/Acpi30.h>
 
 #endif
diff --git a/MdePkg/Include/IndustryStandard/Acpi1_0.h b/MdePkg/Include/IndustryStandard/Acpi1_0.h
index c107da9bd4..4fc05e6fce 100644
--- a/MdePkg/Include/IndustryStandard/Acpi1_0.h
+++ b/MdePkg/Include/IndustryStandard/Acpi1_0.h
@@ -1,7 +1,7 @@
 /** @file   
 	ACPI 1.0b definitions from the ACPI Specification, revision 1.0b
 
-  Copyright (c) 2006 - 2007, Intel Corporation
+  Copyright (c) 2006 - 2008, Intel Corporation
   All rights reserved. This program and the accompanying materials                          
   are licensed and made available under the terms and conditions of the BSD License         
   which accompanies this distribution.  The full text of the license may be found at        
@@ -42,11 +42,14 @@ typedef struct {
 
 #pragma pack()
 //
-// Define for Pci Host Bridge Resource Allocation
+// Define for Desriptor
 //
 #define ACPI_ADDRESS_SPACE_DESCRIPTOR 0x8A
 #define ACPI_END_TAG_DESCRIPTOR       0x79
 
+//
+// Resource Type
+//
 #define ACPI_ADDRESS_SPACE_TYPE_MEM   0x00
 #define ACPI_ADDRESS_SPACE_TYPE_IO    0x01
 #define ACPI_ADDRESS_SPACE_TYPE_BUS   0x02
@@ -56,11 +59,11 @@ typedef struct {
 ///
 #define ACPI_TIMER_FREQUENCY       3579545
 
-//
-// Make sure structures match spec
-//
-#pragma pack(1)
 
+//
+// The commond definition of QWORD, DWORD, and WORD
+// Address Space Descriptors
+//
 typedef struct {
   UINT8   Desc;
   UINT16  Len;
@@ -115,9 +118,6 @@ typedef struct {
 #define EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_TYPE_TRANSLATION          (1 << 5)
 #define EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_TYPE_STATIC               (0 << 5)
 
-#pragma pack()
-
-
 //
 // Ensure proper structure formats
 //
@@ -139,8 +139,8 @@ typedef struct {
 
 //
 // Root System Description Table
-// No definition needed as it is a common description table header followed by a
-// variable number of UINT32 table pointers.
+// No definition needed as it is a common description table header, the same with 
+// EFI_ACPI_DESCRIPTION_HEADER, followed by a variable number of UINT32 table pointers.
 //
 
 ///
@@ -256,7 +256,7 @@ typedef struct {
 
 //
 // Multiple APIC Description Table APIC structure types
-// All other values between 0x09 an 0xFF are reserved and
+// All other values between 0x05 an 0xFF are reserved and
 // will be ignored by OSPM.
 //
 #define EFI_ACPI_1_0_PROCESSOR_LOCAL_APIC           0x00
diff --git a/MdePkg/Include/IndustryStandard/Acpi2_0.h b/MdePkg/Include/IndustryStandard/Acpi2_0.h
index 8462caab3f..0ae652f311 100644
--- a/MdePkg/Include/IndustryStandard/Acpi2_0.h
+++ b/MdePkg/Include/IndustryStandard/Acpi2_0.h
@@ -1,7 +1,7 @@
 /** @file   
 	ACPI 2.0 definitions from the ACPI Specification, revision 2.0
 
-  Copyright (c) 2006 - 2007, Intel Corporation
+  Copyright (c) 2006 - 2008, Intel Corporation
   All rights reserved. This program and the accompanying materials                          
   are licensed and made available under the terms and conditions of the BSD License         
   which accompanies this distribution.  The full text of the license may be found at        
@@ -20,10 +20,6 @@
 // Ensure proper structure formats
 //
 #pragma pack(1)
-//
-// ACPI Specification Revision
-//
-#define EFI_ACPI_2_0_REVISION 0x02
 
 ///
 /// ACPI 2.0 Generic Address Space definition
@@ -81,8 +77,8 @@ typedef struct {
 
 //
 // Root System Description Table
-// No definition needed as it is a common description table header followed by a
-// variable number of UINT32 table pointers.
+// No definition needed as it is a common description table header, the same with 
+// EFI_ACPI_DESCRIPTION_HEADER, followed by a variable number of UINT32 table pointers.
 //
 
 ///
@@ -92,8 +88,8 @@ typedef struct {
 
 //
 // Extended System Description Table
-// No definition needed as it is a common description table header followed by a
-// variable number of UINT64 table pointers.
+// No definition needed as it is a common description table header, the same with 
+// EFI_ACPI_DESCRIPTION_HEADER, followed by a variable number of UINT64 table pointers.
 //
 
 ///
diff --git a/MdePkg/Include/IndustryStandard/Acpi3_0.h b/MdePkg/Include/IndustryStandard/Acpi3_0.h
index cd7d0fbe24..83296e23dd 100644
--- a/MdePkg/Include/IndustryStandard/Acpi3_0.h
+++ b/MdePkg/Include/IndustryStandard/Acpi3_0.h
@@ -1,5 +1,5 @@
 /** @file   
-    ACPI 3.0 definitions from the ACPI Specification Revision 3.0 September 2, 2004
+  ACPI 3.0 definitions from the ACPI Specification Revision 3.0b October 10, 2006
 
   Copyright (c) 2006 - 2008, Intel Corporation
   All rights reserved. This program and the accompanying materials                          
@@ -21,11 +21,6 @@
 //
 #pragma pack(1)
 
-///
-/// ACPI Specification Revision
-///
-#define EFI_ACPI_3_0_REVISION 0x03
-
 ///
 /// ACPI 3.0 Generic Address Space definition
 ///
@@ -76,9 +71,9 @@ typedef struct {
 } EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER;
 
 ///
-/// RSD_PTR Revision (as defined in ACPI 3.0 spec.)
+/// RSD_PTR Revision (as defined in ACPI 3.0b spec.)
 ///
-#define EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER_REVISION 0x02  // ACPISpec30 (Revision 3.0 September 2, 2004) says current value is 2
+#define EFI_ACPI_3_0_ROOT_SYSTEM_DESCRIPTION_POINTER_REVISION 0x02  ///< ACPISpec (Revision 3.0b) says current value is 2
 
 ///
 /// Common table header, this prefaces all ACPI tables, including FACS, but
@@ -91,8 +86,8 @@ typedef struct {
 
 //
 // Root System Description Table
-// No definition needed as it is a common description table header followed by a
-// variable number of UINT32 table pointers.
+// No definition needed as it is a common description table header, the same with 
+// EFI_ACPI_DESCRIPTION_HEADER, followed by a variable number of UINT32 table pointers.
 //
 
 ///
@@ -102,8 +97,8 @@ typedef struct {
 
 //
 // Extended System Description Table
-// No definition needed as it is a common description table header followed by a
-// variable number of UINT64 table pointers.
+// No definition needed as it is a common description table header, the same with 
+// EFI_ACPI_DESCRIPTION_HEADER, followed by a variable number of UINT64 table pointers.
 //
 
 ///
@@ -251,8 +246,8 @@ typedef struct {
 // Differentiated System Description Table,
 // Secondary System Description Table
 // and Persistent System Description Table,
-// no definition needed as they are common description table header followed by a
-// definition block.
+// no definition needed as they are common description table header, the same with
+// EFI_ACPI_DESCRIPTION_HEADER, followed by a definition block.
 //
 #define EFI_ACPI_3_0_DIFFERENTIATED_SYSTEM_DESCRIPTION_TABLE_REVISION   0x02
 #define EFI_ACPI_3_0_SECONDARY_SYSTEM_DESCRIPTION_TABLE_REVISION        0x02