+The
+.B batch-tag
+dump format is intended to more robust against malformed message-ids
+and tags containing whitespace or non-\fBascii\fR(7) characters. This
+format hex-escapes all characters those outside of a small character
+set, intended to be suitable for e.g. pathnames in most UNIX-like
+systems.
+
+.B "notmuch restore"
+updates the maildir flags according to tag changes if the
+.B "maildir.synchronize_flags"
+configuration option is enabled. See \fBnotmuch-config\fR(1) for
+details.
+
+.RE
+
+.RS 4
+.TP 4
+.B auto
+
+This option (the default) tries to guess the format from the
+input. For correctly formed input in either supported format, this
+heuristic, based the fact that batch-tag format contains no parentheses,
+should be accurate.
+
+.RE