Merge branch 'kb/i18n-doc'

* kb/i18n-doc:
  Documentation/i18n.txt: clarify character encoding support

Documentation/i18n.txt

-At the core level, Git is character encoding agnostic.
-
- - The pathnames recorded in the index and in the tree objects
-   are treated as uninterpreted sequences of non-NUL bytes.
-   What readdir(2) returns are what are recorded and compared
-   with the data Git keeps track of, which in turn are expected
-   to be what lstat(2) and creat(2) accepts.  There is no such
-   thing as pathname encoding translation.
+Git is to some extent character encoding agnostic.
 
  - The contents of the blob objects are uninterpreted sequences
    of bytes.  There is no encoding translation at the core
    level.
 
- - The commit log messages are uninterpreted sequences of non-NUL
-   bytes.
+ - Path names are encoded in UTF-8 normalization form C. This
+   applies to tree objects, the index file, ref names, as well as
+   path names in command line arguments, environment variables
+   and config files (`.git/config` (see linkgit:git-config[1]),
+   linkgit:gitignore[5], linkgit:gitattributes[5] and
+   linkgit:gitmodules[5]).
++
+Note that Git at the core level treats path names simply as
+sequences of non-NUL bytes, there are no path name encoding
+conversions (except on Mac and Windows). Therefore, using
+non-ASCII path names will mostly work even on platforms and file
+systems that use legacy extended ASCII encodings. However,
+repositories created on such systems will not work properly on
+UTF-8-based systems (e.g. Linux, Mac, Windows) and vice versa.
+Additionally, many Git-based tools simply assume path names to
+be UTF-8 and will fail to display other encodings correctly.
+
+ - Commit log messages are typically encoded in UTF-8, but other
+   extended ASCII encodings are also supported. This includes
+   ISO-8859-x, CP125x and many others, but _not_ UTF-16/32,
+   EBCDIC and CJK multi-byte encodings (GBK, Shift-JIS, Big5,
+   EUC-x, CP9xx etc.).
 
 Although we encourage that the commit log messages are encoded
 in UTF-8, both the core and Git Porcelain are designed not to