diff --git a/DOC/Methods-Extern.md b/DOC/Methods-Extern.md
index 82449d05..d31e4a46 100644
--- a/DOC/Methods-Extern.md
+++ b/DOC/Methods-Extern.md
@@ -62,9 +62,12 @@ License:
 Zstandard library is provided as open source software using the BSD license.
 
 7-Zip Container Header:
+
+This header is for informational purposes only. It's not mandatory for
+decompressing the data.
 ``` C
  Byte _ver_major; // currently 1
- Byte _ver_minor; // currently 1
+ Byte _ver_minor; // currently 2
  Byte _level;     // currently 1..22
  Byte _reserved[2];
 ```
@@ -116,10 +119,13 @@ License:
 The Brotli library is provided as open source software using the MIT license.
 
 7-Zip Container Header (3 bytes):
+
+This header is for informational purposes only. It's not mandatory for
+decompressing the data.
 ``` C
  Byte _ver_major; // currently 0
  Byte _ver_minor; // currently 6
- Byte _level;     // currently 1..11 (Brotli quality)
+ Byte _level;     // currently 0..11 (Brotli quality)
 ```
 - this header holds some information about the version, which was
   used for creating that 7-Zip container data
@@ -158,6 +164,9 @@ License:
 LZ4 library is provided as open source software using the BSD license.
 
 7-Zip Container Header:
+
+This header is for informational purposes only. It's not mandatory for
+decompressing the data.
 ``` C
  Byte _ver_major;  // currently 1
  Byte _ver_minor;  // currently 7
@@ -206,6 +215,9 @@ License:
 LZ5 library is provided as open source software using the BSD license.
 
 7-Zip Container Header:
+
+This header is for informational purposes only. It's not mandatory for
+decompressing the data.
 ``` C
  Byte _ver_major;  // currently 1
  Byte _ver_minor;  // currently 5
@@ -252,6 +264,9 @@ License:
 Lizard library is provided as open source software using the BSD license.
 
 7-Zip Container Header:
+
+This header is for informational purposes only. It's not mandatory for
+decompressing the data.
 ``` C
  Byte _ver_major;  // currently 2
  Byte _ver_minor;  // currently 0