diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 5ec37c5a7d..e2e0b75cdb 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -1408,18 +1408,32 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiDefaultOemId|"INTEL "|VOID*|0x30001034
 
   ## Default OEM Table ID for ACPI table creation, it is "EDK2    ".
+  #  Accroding to ACPI specification, this field is particularly useful when
+  #  defining a definition block to distinguish definition block functions.
+  #  The OEM assigns each dissimilar table a new OEM Table ID.
+  #  This PCD is ignored for definition block.
   # @Prompt Default OEM Table ID for ACPI table creation.
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiDefaultOemTableId|0x20202020324B4445|UINT64|0x30001035
 
   ## Default OEM Revision for ACPI table creation.
+  #  Accroding to ACPI specification, for LoadTable() opcode, the OS can also
+  #  check the OEM Table ID and Revision ID against a database for a newer
+  #  revision Definition Block of the same OEM Table ID and load it instead.
+  #  This PCD is ignored for definition block.
   # @Prompt Default OEM Revision for ACPI table creation.
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiDefaultOemRevision|0x00000002|UINT32|0x30001036
 
   ## Default Creator ID for ACPI table creation.
+  #  Accroding to ACPI specification, for tables containing Definition Blocks,
+  #  this is the ID for the ASL Compiler.
+  #  This PCD is ignored for definition block.
   # @Prompt Default Creator ID for ACPI table creation.
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiDefaultCreatorId|0x20202020|UINT32|0x30001037
 
   ## Default Creator Revision for ACPI table creation.
+  #  Accroding to ACPI specification, for tables containing Definition Blocks,
+  #  this is the revision for the ASL Compiler.
+  #  This PCD is ignored for definition block.
   # @Prompt Default Creator Revision for ACPI table creation.
   gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiDefaultCreatorRevision|0x01000013|UINT32|0x30001038
 
diff --git a/MdeModulePkg/MdeModulePkg.uni b/MdeModulePkg/MdeModulePkg.uni
index 7ef7d910bf..c026f14534 100644
--- a/MdeModulePkg/MdeModulePkg.uni
+++ b/MdeModulePkg/MdeModulePkg.uni
@@ -225,19 +225,33 @@
 
 #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemTableId_PROMPT  #language en-US "Default OEM Table ID for ACPI table creation"
 
-#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemTableId_HELP  #language en-US "Default OEM Table ID for ACPI table creation."
+#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemTableId_HELP  #language en-US "Default OEM Table ID for ACPI table creation.<BR><BR>\n"
+                                                                                          "Accroding to ACPI specification, this field is particularly useful when\n"
+                                                                                          "defining a definition block to distinguish definition block functions.<BR>\n"
+                                                                                          "The OEM assigns each dissimilar table a new OEM Table ID.<BR>\n"
+                                                                                          "This PCD is ignored for definition block.<BR>"
 
 #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemRevision_PROMPT  #language en-US "Default OEM Revision for ACPI table creation"
 
-#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemRevision_HELP  #language en-US "Default OEM Revision for ACPI table creation."
+#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultOemRevision_HELP  #language en-US "Default OEM Revision for ACPI table creation.<BR><BR>\n"
+                                                                                           "Accroding to ACPI specification, for LoadTable() opcode, the OS can also\n"
+                                                                                           "check the OEM Table ID and Revision ID against a database for a newer\n"
+                                                                                           "revision Definition Block of the same OEM Table ID and load it instead.<BR>\n"
+                                                                                           "This PCD is ignored for definition block.<BR>"
 
 #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultCreatorId_PROMPT  #language en-US "Default Creator ID for ACPI table creation"
 
-#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultCreatorId_HELP  #language en-US "Default Creator ID for ACPI table creation."
+#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultCreatorId_HELP  #language en-US "Default Creator ID for ACPI table creation.<BR><BR>\n"
+                                                                                         "Accroding to ACPI specification, for tables containing Definition Blocks,\n"
+                                                                                         "this is the ID for the ASL Compiler.<BR>\n"
+                                                                                         "This PCD is ignored for definition block.<BR>"
 
 #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultCreatorRevision_PROMPT  #language en-US "Default Creator Revision for ACPI table creation"
 
-#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultCreatorRevision_HELP  #language en-US "Default Creator Revision for ACPI table creation."
+#string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdAcpiDefaultCreatorRevision_HELP  #language en-US "Default Creator Revision for ACPI table creation.<BR><BR>\n"
+                                                                                               "Accroding to ACPI specification, for tables containing Definition Blocks,\n"
+                                                                                               "this is the revision for the ASL Compiler.<BR>\n"
+                                                                                               "This PCD is ignored for definition block.<BR>"
 
 #string STR_gEfiMdeModulePkgTokenSpaceGuid_PcdMemoryProfilePropertyMask_PROMPT  #language en-US "Memory Profile Property"