diff --git a/MdePkg/Include/Guid/DebugImageInfoTable.h b/MdePkg/Include/Guid/DebugImageInfoTable.h
index c26ba10e26..0b56c2035e 100644
--- a/MdePkg/Include/Guid/DebugImageInfoTable.h
+++ b/MdePkg/Include/Guid/DebugImageInfoTable.h
@@ -25,7 +25,8 @@
 #define EFI_DEBUG_IMAGE_INFO_UPDATE_IN_PROGRESS  0x01
 #define EFI_DEBUG_IMAGE_INFO_TABLE_MODIFIED      0x02
 
-#define EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL  0x01
+#define EFI_DEBUG_IMAGE_INFO_TYPE_LEGACY_PE   0x01
+#define EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL      0x02
 
 typedef struct {
   UINT64                  Signature;          ///< A constant UINT64 that has the value EFI_SYSTEM_TABLE_SIGNATURE
@@ -35,8 +36,14 @@ typedef struct {
 
 typedef struct {
   ///
-  /// Indicates the type of image info structure. For PE32 EFI images,
-  /// this is set to EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL.
+  /// Indicates the available image info in this structure.
+  /// EFI_DEBUG_IMAGE_INFO_TYPE_NORMAL (i.e. 2) indicates that PdbPath and
+  //  DebugBase fields are present (the loaded image may or may not be a PE).
+  /// Note that EFI_DEBUG_IMAGE_INFO_TYPE_LEGACY_PE (i.e. 1) was used in
+  /// earlier versions to indicate that the loaded image is a PE, using a
+  /// previous version of this structure which did not include the PdbPath
+  /// and DebugBase fields (therefore knowledge of the specific image type
+  /// was required in order to access debug symbolication information).
   ///
   UINT32                       ImageInfoType;
   ///
@@ -47,7 +54,13 @@ typedef struct {
   /// Indicates the image handle of the associated image.
   ///
   EFI_HANDLE                   ImageHandle;
-  CHAR8                      *PdbPath;
+  ///
+  /// Symbol file path for debug symbolication.
+  ///
+  CHAR8                        *PdbPath;
+  ///
+  /// Image base address for debug symbolication.
+  ///
   UINTN                        DebugBase;
 } EFI_DEBUG_IMAGE_INFO_NORMAL;