wimlib.h documentation

[wimlib] / README

diff --git a/README b/README
index 6542e251d5f03cdfeb1175dbc67ab5bf0a7da9d1..39f447842f6fef6e4e04d9765cc2ccdcd07dcaf0 100644 (file)
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+++ b/README
@@ -6,6 +6,25 @@ files are normally created by using the `imagex.exe' utility on Windows,
 but this library provides a free implementetion of imagex for UNIX-based
 systems.
 
 but this library provides a free implementetion of imagex for UNIX-based
 systems.
 

+                                  WIM FILES
+
+A Windows Imaging (WIM) file is an archive.  Like some other archive formats
+such as ZIP, files in WIM archives may be compressed.  WIM archives support two
+Microsoft-specific compression formats:  LZX and XPRESS.  Both are based on LZ77
+and Huffman encoding, and both are supported by wimlib.
+
+Unlike ZIP files, WIM files can contain multiple independent toplevel directory
+trees known as images.  While each image has its own metadata describing a
+directory tree and file access modes, files are not duplicated for each image;
+instead, each file is included only once in the entire WIM.  Microsoft did this
+so that in one WIM file, they could do things like have 5 different versions of
+Windows that are almost exactly the same.
+
+Microsoft provides documentation for the WIM file format, XPRESS compression
+format, and LZX compression format.  The XPRESS documentation is acceptable, but
+the LZX documentation is not entirely correct, and the WIM documentation itself
+is very incomplete and is of unacceptable quality.
+

                                   WINDOWS PE
 
 A major use for this library is to create customized images of Windows PE, the
                                   WINDOWS PE
 
 A major use for this library is to create customized images of Windows PE, the