-the destination machine as an additional directory to compare destination
-files against when doing transfers if the files are missing in the
-destination directory. Files that are identical to one of the specified
-directories are not transferred. This is useful for creating a sparse
-backup into a new hierarchy. If em(DIR) is a relative path, it is relative
-to the destination directory. See also --copy-dest and --link-dest.
+the destination machine as an additional hierarchy to compare destination
+files against doing transfers (if the files are missing in the destination
+directory). If a file is found in em(DIR) that is identical to the
+sender's file, the file will NOT be transferred to the destination
+directory. This is useful for creating a sparse backup of just files that
+have changed from an earlier backup.
+
+Beginning in version 2.6.4, multiple --compare-dest directories may be
+provided and rsync will search the list in the order specified until it
+finds an existing file. That first discovery is used as the basis file,
+and also determines if the transfer needs to happen.
+
+If em(DIR) is a relative path, it is relative to the destination directory.
+See also --copy-dest and --link-dest.