diff --git a/MdePkg/Include/IndustryStandard/Acpi10.h b/MdePkg/Include/IndustryStandard/Acpi10.h
index bd05553e04..c05a6051b4 100644
--- a/MdePkg/Include/IndustryStandard/Acpi10.h
+++ b/MdePkg/Include/IndustryStandard/Acpi10.h
@@ -23,11 +23,9 @@ typedef struct {
   UINT32  Length;
 } EFI_ACPI_COMMON_HEADER;
 
-//
-// Common ACPI description table header.  This structure prefaces most ACPI tables.
-//
-#pragma pack(1)
-
+///
+/// Common ACPI description table header.  This structure prefaces most ACPI tables.
+///
 typedef struct {
   UINT32  Signature;
   UINT32  Length;
@@ -40,7 +38,6 @@ typedef struct {
   UINT32  CreatorRevision;
 } EFI_ACPI_DESCRIPTION_HEADER;
 
-#pragma pack()
 //
 // Define for Desriptor
 //
@@ -63,10 +60,11 @@ typedef struct {
 // Ensure proper structure formats
 //
 #pragma pack(1)
-//
-// The commond definition of QWORD, DWORD, and WORD
-// Address Space Descriptors
-//
+
+///
+/// The commond definition of QWORD, DWORD, and WORD
+/// Address Space Descriptors
+///
 typedef struct {
   UINT8   Desc;
   UINT16  Len;
@@ -123,10 +121,6 @@ typedef struct {
 #define EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_TYPE_TRANSLATION          (1 << 5)
 #define EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_TYPE_STATIC               (0 << 5)
 
-//
-// Ensure proper structure formats
-//
-#pragma pack(1)
 //
 // ACPI 1.0b table structures
 //
@@ -208,16 +202,16 @@ typedef struct {
 // Fixed ACPI Description Table Fixed Feature Flags
 // All other bits are reserved and must be set to 0.
 //
-#define EFI_ACPI_1_0_WBINVD       (1 << 0)
-#define EFI_ACPI_1_0_WBINVD_FLUSH (1 << 1)
-#define EFI_ACPI_1_0_PROC_C1      (1 << 2)
-#define EFI_ACPI_1_0_P_LVL2_UP    (1 << 3)
-#define EFI_ACPI_1_0_PWR_BUTTON   (1 << 4)
-#define EFI_ACPI_1_0_SLP_BUTTON   (1 << 5)
-#define EFI_ACPI_1_0_FIX_RTC      (1 << 6)
-#define EFI_ACPI_1_0_RTC_S4       (1 << 7)
-#define EFI_ACPI_1_0_TMR_VAL_EXT  (1 << 8)
-#define EFI_ACPI_1_0_DCK_CAP      (1 << 9)
+#define EFI_ACPI_1_0_WBINVD               BIT0
+#define EFI_ACPI_1_0_WBINVD_FLUSH         BIT1
+#define EFI_ACPI_1_0_PROC_C1              BIT2
+#define EFI_ACPI_1_0_P_LVL2_UP            BIT3
+#define EFI_ACPI_1_0_PWR_BUTTON           BIT4
+#define EFI_ACPI_1_0_SLP_BUTTON           BIT5
+#define EFI_ACPI_1_0_FIX_RTC              BIT6
+#define EFI_ACPI_1_0_RTC_S4               BIT7
+#define EFI_ACPI_1_0_TMR_VAL_EXT          BIT8
+#define EFI_ACPI_1_0_DCK_CAP              BIT9
 
 ///
 /// Firmware ACPI Control Structure
@@ -236,7 +230,7 @@ typedef struct {
 /// Firmware Control Structure Feature Flags
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_1_0_S4BIOS_F (1 << 0)
+#define EFI_ACPI_1_0_S4BIOS_F             BIT0
 
 ///
 /// Multiple APIC Description Table header definition.  The rest of the table
@@ -257,7 +251,7 @@ typedef struct {
 /// Multiple APIC Flags
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_1_0_PCAT_COMPAT  (1 << 0)
+#define EFI_ACPI_1_0_PCAT_COMPAT           BIT0
 
 //
 // Multiple APIC Description Table APIC structure types
@@ -288,7 +282,7 @@ typedef struct {
 ///
 /// Local APIC Flags.  All other bits are reserved and must be 0.
 ///
-#define EFI_ACPI_1_0_LOCAL_APIC_ENABLED (1 << 0)
+#define EFI_ACPI_1_0_LOCAL_APIC_ENABLED      BIT0
 
 ///
 /// IO APIC Structure
@@ -324,6 +318,11 @@ typedef struct {
   UINT32  GlobalSystemInterruptVector;
 } EFI_ACPI_1_0_NON_MASKABLE_INTERRUPT_SOURCE_STRUCTURE;
 
+//
+// Ensure proper structure formats
+//
+#pragma pack(1)
+
 ///
 /// Local APIC NMI Structure
 ///
@@ -335,6 +334,8 @@ typedef struct {
   UINT8   LocalApicInti;
 } EFI_ACPI_1_0_LOCAL_APIC_NMI_STRUCTURE;
 
+#pragma pack()
+
 ///
 /// Smart Battery Description Table (SBST)
 ///
@@ -394,6 +395,4 @@ typedef struct {
 ///
 #define EFI_ACPI_1_0_SECONDARY_SYSTEM_DESCRIPTION_TABLE_SIGNATURE  SIGNATURE_32('S', 'S', 'D', 'T')
 
-#pragma pack()
-
 #endif
diff --git a/MdePkg/Include/IndustryStandard/Acpi20.h b/MdePkg/Include/IndustryStandard/Acpi20.h
index 9c1db57a42..b67ee54440 100644
--- a/MdePkg/Include/IndustryStandard/Acpi20.h
+++ b/MdePkg/Include/IndustryStandard/Acpi20.h
@@ -32,6 +32,8 @@ typedef struct {
   UINT64  Address;
 } EFI_ACPI_2_0_GENERIC_ADDRESS_STRUCTURE;
 
+#pragma pack()
+
 //
 // Generic Address Space Address IDs
 //
@@ -160,31 +162,31 @@ typedef struct {
 ///
 #define EFI_ACPI_2_0_FIXED_ACPI_DESCRIPTION_TABLE_REVISION  0x03
 
-///
-/// Fixed ACPI Description Table Boot Architecture Flags
-/// All other bits are reserved and must be set to 0.
-///
-#define EFI_ACPI_2_0_LEGACY_DEVICES (1 << 0)
-#define EFI_ACPI_2_0_8042           (1 << 1)
+//
+// Fixed ACPI Description Table Boot Architecture Flags
+// All other bits are reserved and must be set to 0.
+//
+#define EFI_ACPI_2_0_LEGACY_DEVICES          BIT0
+#define EFI_ACPI_2_0_8042                    BIT1
 
 //
 // Fixed ACPI Description Table Fixed Feature Flags
 // All other bits are reserved and must be set to 0.
 //
-#define EFI_ACPI_2_0_WBINVD         (1 << 0)
-#define EFI_ACPI_2_0_WBINVD_FLUSH   (1 << 1)
-#define EFI_ACPI_2_0_PROC_C1        (1 << 2)
-#define EFI_ACPI_2_0_P_LVL2_UP      (1 << 3)
-#define EFI_ACPI_2_0_PWR_BUTTON     (1 << 4)
-#define EFI_ACPI_2_0_SLP_BUTTON     (1 << 5)
-#define EFI_ACPI_2_0_FIX_RTC        (1 << 6)
-#define EFI_ACPI_2_0_RTC_S4         (1 << 7)
-#define EFI_ACPI_2_0_TMR_VAL_EXT    (1 << 8)
-#define EFI_ACPI_2_0_DCK_CAP        (1 << 9)
-#define EFI_ACPI_2_0_RESET_REG_SUP  (1 << 10)
-#define EFI_ACPI_2_0_SEALED_CASE    (1 << 11)
-#define EFI_ACPI_2_0_HEADLESS       (1 << 12)
-#define EFI_ACPI_2_0_CPU_SW_SLP     (1 << 13)
+#define EFI_ACPI_2_0_WBINVD                  BIT0
+#define EFI_ACPI_2_0_WBINVD_FLUSH            BIT1
+#define EFI_ACPI_2_0_PROC_C1                 BIT2
+#define EFI_ACPI_2_0_P_LVL2_UP               BIT3
+#define EFI_ACPI_2_0_PWR_BUTTON              BIT4
+#define EFI_ACPI_2_0_SLP_BUTTON              BIT5
+#define EFI_ACPI_2_0_FIX_RTC                 BIT6
+#define EFI_ACPI_2_0_RTC_S4                  BIT7
+#define EFI_ACPI_2_0_TMR_VAL_EXT             BIT8
+#define EFI_ACPI_2_0_DCK_CAP                 BIT9
+#define EFI_ACPI_2_0_RESET_REG_SUP           BIT10
+#define EFI_ACPI_2_0_SEALED_CASE             BIT11
+#define EFI_ACPI_2_0_HEADLESS                BIT12
+#define EFI_ACPI_2_0_CPU_SW_SLP              BIT13
 
 ///
 /// Firmware ACPI Control Structure
@@ -210,7 +212,7 @@ typedef struct {
 /// Firmware Control Structure Feature Flags
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_2_0_S4BIOS_F (1 << 0)
+#define EFI_ACPI_2_0_S4BIOS_F        BIT0
 
 ///
 /// Multiple APIC Description Table header definition.  The rest of the table
@@ -231,7 +233,7 @@ typedef struct {
 /// Multiple APIC Flags
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_2_0_PCAT_COMPAT  (1 << 0)
+#define EFI_ACPI_2_0_PCAT_COMPAT          BIT0
 
 //
 // Multiple APIC Description Table APIC structure types
@@ -266,7 +268,7 @@ typedef struct {
 ///
 /// Local APIC Flags.  All other bits are reserved and must be 0.
 ///
-#define EFI_ACPI_2_0_LOCAL_APIC_ENABLED (1 << 0)
+#define EFI_ACPI_2_0_LOCAL_APIC_ENABLED         BIT0
 
 ///
 /// IO APIC Structure
@@ -302,6 +304,11 @@ typedef struct {
   UINT32  GlobalSystemInterrupt;
 } EFI_ACPI_2_0_NON_MASKABLE_INTERRUPT_SOURCE_STRUCTURE;
 
+//
+// Ensure proper structure formats
+//
+#pragma pack(1)
+
 ///
 /// Local APIC NMI Structure
 ///
@@ -323,6 +330,8 @@ typedef struct {
   UINT64  LocalApicAddress;
 } EFI_ACPI_2_0_LOCAL_APIC_ADDRESS_OVERRIDE_STRUCTURE;
 
+#pragma pack()
+
 ///
 /// IO SAPIC Structure
 ///
@@ -503,6 +512,4 @@ typedef struct {
 ///
 #define EFI_ACPI_2_0_MEMORY_MAPPED_CONFIGURATION_BASE_ADDRESS_TABLE_SIGNATURE  SIGNATURE_32('M', 'C', 'F', 'G')
 
-#pragma pack()
-
 #endif
diff --git a/MdePkg/Include/IndustryStandard/Acpi30.h b/MdePkg/Include/IndustryStandard/Acpi30.h
index 75b5f8eba8..d07cce5807 100644
--- a/MdePkg/Include/IndustryStandard/Acpi30.h
+++ b/MdePkg/Include/IndustryStandard/Acpi30.h
@@ -1,5 +1,5 @@
 /** @file   
-  ACPI 3.0 definitions from the ACPI Specification Revision 3.0b October 10, 2006
+  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                          
@@ -31,6 +31,8 @@ typedef struct {
   UINT8   AccessSize;
   UINT64  Address;
 } EFI_ACPI_3_0_GENERIC_ADDRESS_STRUCTURE;
+     
+#pragma pack()
 
 //
 // Generic Address Space Address IDs
@@ -185,36 +187,36 @@ typedef struct {
 // Fixed ACPI Description Table Boot Architecture Flags
 // All other bits are reserved and must be set to 0.
 //
-#define EFI_ACPI_3_0_LEGACY_DEVICES     (1 << 0)
-#define EFI_ACPI_3_0_8042               (1 << 1)
-#define EFI_ACPI_3_0_VGA_NOT_PRESENT    (1 << 2)
-#define EFI_ACPI_3_0_MSI_NOT_SUPPORTED  (1 << 3)
-#define EFI_ACPI_3_0_PCIE_ASPM_CONTROLS (1 << 4)
+#define EFI_ACPI_3_0_LEGACY_DEVICES              BIT0
+#define EFI_ACPI_3_0_8042                        BIT1
+#define EFI_ACPI_3_0_VGA_NOT_PRESENT             BIT2
+#define EFI_ACPI_3_0_MSI_NOT_SUPPORTED           BIT3
+#define EFI_ACPI_3_0_PCIE_ASPM_CONTROLS          BIT4
 
 //
 // Fixed ACPI Description Table Fixed Feature Flags
 // All other bits are reserved and must be set to 0.
 //
-#define EFI_ACPI_3_0_WBINVD                   (1 << 0)
-#define EFI_ACPI_3_0_WBINVD_FLUSH             (1 << 1)
-#define EFI_ACPI_3_0_PROC_C1                  (1 << 2)
-#define EFI_ACPI_3_0_P_LVL2_UP                (1 << 3)
-#define EFI_ACPI_3_0_PWR_BUTTON               (1 << 4)
-#define EFI_ACPI_3_0_SLP_BUTTON               (1 << 5)
-#define EFI_ACPI_3_0_FIX_RTC                  (1 << 6)
-#define EFI_ACPI_3_0_RTC_S4                   (1 << 7)
-#define EFI_ACPI_3_0_TMR_VAL_EXT              (1 << 8)
-#define EFI_ACPI_3_0_DCK_CAP                  (1 << 9)
-#define EFI_ACPI_3_0_RESET_REG_SUP            (1 << 10)
-#define EFI_ACPI_3_0_SEALED_CASE              (1 << 11)
-#define EFI_ACPI_3_0_HEADLESS                 (1 << 12)
-#define EFI_ACPI_3_0_CPU_SW_SLP               (1 << 13)
-#define EFI_ACPI_3_0_PCI_EXP_WAK              (1 << 14)
-#define EFI_ACPI_3_0_USE_PLATFORM_CLOCK       (1 << 15)
-#define EFI_ACPI_3_0_S4_RTC_STS_VALID         (1 << 16)
-#define EFI_ACPI_3_0_REMOTE_POWER_ON_CAPABLE  (1 << 17)
-#define EFI_ACPI_3_0_FORCE_APIC_CLUSTER_MODEL (1 << 18)
-#define EFI_ACPI_3_0_FORCE_APIC_PHYSICAL_DESTINATION_MODE (1 << 19)
+#define EFI_ACPI_3_0_WBINVD                                 BIT0
+#define EFI_ACPI_3_0_WBINVD_FLUSH                           BIT1
+#define EFI_ACPI_3_0_PROC_C1                                BIT2
+#define EFI_ACPI_3_0_P_LVL2_UP                              BIT3
+#define EFI_ACPI_3_0_PWR_BUTTON                             BIT4
+#define EFI_ACPI_3_0_SLP_BUTTON                             BIT5
+#define EFI_ACPI_3_0_FIX_RTC                                BIT6
+#define EFI_ACPI_3_0_RTC_S4                                 BIT7
+#define EFI_ACPI_3_0_TMR_VAL_EXT                            BIT8
+#define EFI_ACPI_3_0_DCK_CAP                                BIT9
+#define EFI_ACPI_3_0_RESET_REG_SUP                          BIT10
+#define EFI_ACPI_3_0_SEALED_CASE                            BIT11
+#define EFI_ACPI_3_0_HEADLESS                               BIT12
+#define EFI_ACPI_3_0_CPU_SW_SLP                             BIT13
+#define EFI_ACPI_3_0_PCI_EXP_WAK                            BIT14
+#define EFI_ACPI_3_0_USE_PLATFORM_CLOCK                     BIT15
+#define EFI_ACPI_3_0_S4_RTC_STS_VALID                       BIT16
+#define EFI_ACPI_3_0_REMOTE_POWER_ON_CAPABLE                BIT17
+#define EFI_ACPI_3_0_FORCE_APIC_CLUSTER_MODEL               BIT18
+#define EFI_ACPI_3_0_FORCE_APIC_PHYSICAL_DESTINATION_MODE   BIT19
 
 ///
 /// Firmware ACPI Control Structure
@@ -240,7 +242,7 @@ typedef struct {
 /// Firmware Control Structure Feature Flags
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_3_0_S4BIOS_F (1 << 0)
+#define EFI_ACPI_3_0_S4BIOS_F       BIT0
 
 //
 // Differentiated System Description Table,
@@ -271,7 +273,7 @@ typedef struct {
 /// Multiple APIC Flags
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_3_0_PCAT_COMPAT  (1 << 0)
+#define EFI_ACPI_3_0_PCAT_COMPAT         BIT0
 
 //
 // Multiple APIC Description Table APIC structure types
@@ -306,7 +308,7 @@ typedef struct {
 ///
 /// Local APIC Flags.  All other bits are reserved and must be 0.
 ///
-#define EFI_ACPI_3_0_LOCAL_APIC_ENABLED (1 << 0)
+#define EFI_ACPI_3_0_LOCAL_APIC_ENABLED        BIT0
 
 ///
 /// IO APIC Structure
@@ -365,6 +367,11 @@ typedef struct {
   UINT16  Flags;
   UINT32  GlobalSystemInterrupt;
 } EFI_ACPI_3_0_NON_MASKABLE_INTERRUPT_SOURCE_STRUCTURE;
+  
+//
+// Ensure proper structure formats
+//
+#pragma pack(1)
 
 ///
 /// Local APIC NMI Structure
@@ -387,6 +394,8 @@ typedef struct {
   UINT64  LocalApicAddress;
 } EFI_ACPI_3_0_LOCAL_APIC_ADDRESS_OVERRIDE_STRUCTURE;
 
+#pragma pack()
+
 ///
 /// IO SAPIC Structure
 ///
@@ -433,7 +442,7 @@ typedef struct {
 /// Platform Interrupt Source Flags.
 /// All other bits are reserved and must be set to 0.
 ///
-#define EFI_ACPI_3_0_CPEI_PROCESSOR_OVERRIDE     (1 << 0)
+#define EFI_ACPI_3_0_CPEI_PROCESSOR_OVERRIDE          BIT0
 
 ///
 /// Smart Battery Description Table (SBST)
@@ -474,7 +483,7 @@ typedef struct {
 ///
 typedef struct {
   EFI_ACPI_DESCRIPTION_HEADER Header;
-  UINT32                      Reserved1;  // Must be set to 1
+  UINT32                      Reserved1;  ///< Must be set to 1
   UINT64                      Reserved2;
 } EFI_ACPI_3_0_SYSTEM_RESOURCE_AFFINITY_TABLE_HEADER;
 
@@ -483,11 +492,11 @@ typedef struct {
 ///
 #define EFI_ACPI_3_0_SYSTEM_RESOURCE_AFFINITY_TABLE_REVISION  0x02
 
-///
-/// SRAT structure types.
-/// All other values between 0x02 an 0xFF are reserved and
-/// will be ignored by OSPM.
-///
+//
+// SRAT structure types.
+// All other values between 0x02 an 0xFF are reserved and
+// will be ignored by OSPM.
+//
 #define EFI_ACPI_3_0_PROCESSOR_LOCAL_APIC_SAPIC_AFFINITY  0x00
 #define EFI_ACPI_3_0_MEMORY_AFFINITY                      0x01
 
@@ -510,6 +519,10 @@ typedef struct {
 ///
 #define EFI_ACPI_3_0_PROCESSOR_LOCAL_APIC_SAPIC_ENABLED (1 << 0)
 
+//
+// Ensure proper structure formats
+//
+#pragma pack(1)
 ///
 /// Memory Affinity Structure Definition
 ///
@@ -527,6 +540,8 @@ typedef struct {
   UINT64  Reserved3;
 } EFI_ACPI_3_0_MEMORY_AFFINITY_STRUCTURE;
 
+#pragma pack()
+
 //
 // Memory Flags.  All other bits are reserved and must be 0.
 //
@@ -678,6 +693,4 @@ typedef struct {
 ///
 #define EFI_ACPI_3_0_ISCSI_BOOT_FIRMWARE_TABLE_SIGNATURE  SIGNATURE_32('i', 'B', 'F', 'T')
 
-#pragma pack()
-
 #endif
diff --git a/MdePkg/Include/IndustryStandard/AlertStandardFormatTable.h b/MdePkg/Include/IndustryStandard/AlertStandardFormatTable.h
index ef2462e654..13a0b90768 100644
--- a/MdePkg/Include/IndustryStandard/AlertStandardFormatTable.h
+++ b/MdePkg/Include/IndustryStandard/AlertStandardFormatTable.h
@@ -16,11 +16,6 @@
 
 #include <IndustryStandard/Acpi.h>
 
-//
-// Ensure proper structure formats
-//
-#pragma pack (1)
-
 ///
 /// Information Record header that appears at the beginning of each record
 ///
@@ -141,6 +136,4 @@ typedef EFI_ACPI_DESCRIPTION_HEADER EFI_ACPI_ASF_DESCRIPTION_HEADER;
 ///
 #define EFI_ACPI_ASF_DESCRIPTION_TABLE_SIGNATURE  SIGNATURE_32 ('A', 'S', 'F', '!')
 
-#pragma pack ()
-
-#endif // _ALERT_STANDARD_FORMAT_TABLE_H
+#endif 
diff --git a/MdePkg/Include/IndustryStandard/Atapi.h b/MdePkg/Include/IndustryStandard/Atapi.h
index 0f34d8dfc4..3986366c02 100644
--- a/MdePkg/Include/IndustryStandard/Atapi.h
+++ b/MdePkg/Include/IndustryStandard/Atapi.h
@@ -16,8 +16,6 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #ifndef _ATAPI_H_
 #define _ATAPI_H_
 
-#pragma pack(1)
-
 ///
 /// ATAPI_IDENTIFY_DATA is defined in ATA-6
 ///
@@ -141,9 +139,9 @@ typedef struct {
   UINT8 additional_sense_bytes_18_253[253 - 18 + 1];
 } ATAPI_REQUEST_SENSE_DATA;
 
-///
-/// The followings are defined in SFF-8070i(ATAPI Removable Rewritable Specification)
-///
+//
+// The followings are defined in SFF-8070i(ATAPI Removable Rewritable Specification)
+//
 
 ///
 /// READ CAPACITY Data 
@@ -306,8 +304,6 @@ typedef union {
   ATAPI_READ_FORMAT_CAP_CMD ReadFormatCapacity;
 } ATAPI_PACKET_COMMAND;
 
-#pragma pack()
-
 
 #define ATAPI_MAX_DMA_EXT_CMD_SECTORS 0x10000
 #define ATAPI_MAX_DMA_CMD_SECTORS     0x100
@@ -342,7 +338,6 @@ typedef union {
 #define ATA_CMD_READ_LONG_WITH_RETRY    0x23   ///< defined in ATA-5
 #define ATA_CMD_READ_SECTORS_EXT        0x24   ///< defined in ATA-6
 
-
 //
 // Class 2: PIO Data-Out Commands
 //
@@ -391,7 +386,6 @@ typedef union {
 #define ATA_SMART_ENABLE_OPERATION  0xd8
 #define ATA_SMART_RETURN_STATUS     0xda
 
-
 ///
 /// Class 4: DMA Command
 ///
@@ -401,9 +395,7 @@ typedef union {
 #define ATA_CMD_WRITE_DMA             0xca   ///< defined in ATA-6
 #define ATA_CMD_WRITE_DMA_WITH_RETRY  0xcb   ///< defined in ATA-4
 #define ATA_CMD_WRITE_DMA_EXT         0x35   ///< defined in ATA-6
-
-
-
+        
 ///
 /// default content of device control register, disable INT,
 /// Bit3 is set to 1 according ATA-1
@@ -419,12 +411,12 @@ typedef union {
 
 #define ATA_REQUEST_SENSE_ERROR (0x70) ///< defined in SFF-8070i
 
-///
-/// Sense Key, Additional Sense Codes and Additional Sense Code Qualifier
-/// defined in MultiMedia Commands (MMC, MMC-2) 
-///
-/// Sense Key 
-///
+//
+// Sense Key, Additional Sense Codes and Additional Sense Code Qualifier
+// defined in MultiMedia Commands (MMC, MMC-2) 
+//
+// Sense Key 
+//
 #define ATA_SK_NO_SENSE         (0x0)
 #define ATA_SK_RECOVERY_ERROR   (0x1)
 #define ATA_SK_NOT_READY        (0x2)
@@ -442,9 +434,9 @@ typedef union {
 #define ATA_SK_MISCOMPARE       (0xE)
 #define ATA_SK_RESERVED_F       (0xF)
 
-///
-/// Additional Sense Codes
-///
+//
+// Additional Sense Codes
+//
 #define ATA_ASC_NOT_READY                   (0x04)
 #define ATA_ASC_MEDIA_ERR1                  (0x10)
 #define ATA_ASC_MEDIA_ERR2                  (0x11)
@@ -466,9 +458,9 @@ typedef union {
 //
 #define ATA_ASCQ_IN_PROGRESS  (0x01)
 
-///
-/// Error Register
-///
+//
+// Error Register
+//
 #define ATA_ERRREG_BBK   BIT7  ///< Bad block detected      defined in ATA-1
 #define ATA_ERRREG_UNC   BIT6  ///< Uncorrectable Data      defined in ATA-3
 #define ATA_ERRREG_MC    BIT5  ///< Media Change            defined in ATA-3
@@ -478,9 +470,9 @@ typedef union {
 #define ATA_ERRREG_TK0NF BIT1  ///< Track 0 Not Found       defined in ATA-3
 #define ATA_ERRREG_AMNF  BIT0  ///< Address Mark Not Found  defined in ATA-3
 
-///
-/// Status Register
-///
+//
+// Status Register
+//
 #define ATA_STSREG_BSY   BIT7  ///< Controller Busy         defined in ATA-6
 #define ATA_STSREG_DRDY  BIT6  ///< Drive Ready             defined in ATA-6
 #define ATA_STSREG_DWF   BIT5  ///< Drive Write Fault       defined in ATA-6
@@ -490,9 +482,9 @@ typedef union {
 #define ATA_STSREG_IDX   BIT1  ///< Index                   defined in ATA-3
 #define ATA_STSREG_ERR   BIT0  ///< Error                   defined in ATA-6
 
-///
-/// Device Control Register
-///
+//
+// Device Control Register
+//
 #define ATA_CTLREG_SRST  BIT2  ///< Software Reset
 #define ATA_CTLREG_IEN_L BIT1  ///< Interrupt Enable #
 
diff --git a/MdePkg/Include/IndustryStandard/ElTorito.h b/MdePkg/Include/IndustryStandard/ElTorito.h
index 12375015ef..4933dd786f 100644
--- a/MdePkg/Include/IndustryStandard/ElTorito.h
+++ b/MdePkg/Include/IndustryStandard/ElTorito.h
@@ -19,9 +19,9 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #ifndef _ELTORITO_H_
 #define _ELTORITO_H_
 
-///
-/// CDROM_VOLUME_DESCRIPTOR.Types, defined in ISO 9660
-///
+//
+// CDROM_VOLUME_DESCRIPTOR.Types, defined in ISO 9660
+//
 #define CDVOL_TYPE_STANDARD 0x0
 #define CDVOL_TYPE_CODED    0x1
 #define CDVOL_TYPE_END      0xFF
@@ -55,8 +55,6 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 #define ELTORITO_HARD_DISK    0x04
 
 
-#pragma pack(1)
-
 /// 
 /// CD-ROM Volume Descriptor
 /// 
@@ -136,6 +134,4 @@ typedef union {
 
 } ELTORITO_CATALOG;
 
-#pragma pack()
-
 #endif
diff --git a/MdePkg/Include/IndustryStandard/HighPrecisionEventTimerTable.h b/MdePkg/Include/IndustryStandard/HighPrecisionEventTimerTable.h
index ef1fe149cf..bb6c25740e 100644
--- a/MdePkg/Include/IndustryStandard/HighPrecisionEventTimerTable.h
+++ b/MdePkg/Include/IndustryStandard/HighPrecisionEventTimerTable.h
@@ -34,6 +34,8 @@ typedef struct {
   UINT8                                   PageProtectionAndOemAttribute;
 } EFI_ACPI_HIGH_PRECISION_EVENT_TIMER_TABLE_HEADER;
 
+#pragma pack()
+
 ///
 /// HPET Revision (defined in spec)
 ///
@@ -47,6 +49,4 @@ typedef struct {
 #define EFI_ACPI_4KB_PAGE_PROTECTION  1
 #define EFI_ACPI_64KB_PAGE_PROTECTION 2
 
-#pragma pack()
-
 #endif