--index-version <n>::
Write the resulting index out in the named on-disk format version.
- The current default version is 2.
+ Supported versions are 2, 3 and 4. The current default version is 2
+ or 3, depending on whether extra features are used, such as
+ `git add -N`.
++
+Version 4 performs a simple pathname compression that reduces index
+size by 30%-50% on large repositories, which results in faster load
+time. Version 4 is relatively young (first released in in 1.8.0 in
+October 2012). Other Git implementations such as JGit and libgit2
+may not support it yet.
-z::
Only meaningful with `--stdin` or `--index-info`; paths are
------------
The first line of the input feeds 0 as the mode to remove the
-path; the SHA1 does not matter as long as it is well formatted.
+path; the SHA-1 does not matter as long as it is well formatted.
Then the second and third line feeds stage 1 and stage 2 entries
for that path. After the above, we would end up with this: