Make usage documentation for git-add consistent.

diff --git a/Documentation/diff-format.txt b/Documentation/diff-format.txt
index 18d49d2c3baa81983b19a938598eb091fb7809ef..001503205b24d5c20ec10792c4ab6c4c7221bcb7 100644 (file)
--- a/Documentation/diff-format.txt
+++ b/Documentation/diff-format.txt
@@ -126,6 +126,13 @@ the file that rename/copy produces, respectively.
     If there is need for such substitution then the whole
     pathname is put in double quotes.
 
+The similarity index is the percentage of unchanged lines, and
+the dissimilarity index is the percentage of changed lines.  It
+is a rounded down integer, followed by a percent sign.  The
+similarity index value of 100% is thus reserved for two equal
+files, while 100% dissimilarity means that no line from the old
+file made it into the new one.
+
 
 combined diff format
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