From 956fa92a539bce56793912ee1d68f70d97364ecb Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Tue, 27 Sep 2022 20:32:03 +0300
Subject: [PATCH] Update revision history

---
 doc/system/changes.adoc | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/doc/system/changes.adoc b/doc/system/changes.adoc
index 513372e..422b421 100644
--- a/doc/system/changes.adoc
+++ b/doc/system/changes.adoc
@@ -8,6 +8,13 @@ https://www.boost.org/LICENSE_1_0.txt
 # Revision History
 :idprefix:
 
+## Changes in Boost 1.81
+
+* The macro `BOOST_SYSTEM_DISABLE_THREADS` can now be defined to disable
+  the use of `<mutex>` (e.g. on single-threaded libstdc++).
+* Added `value_type`, `error_type`, `in_place_value`, `in_place_error`
+  to `result<>`.
+
 ## Changes in Boost 1.80
 
 * When an `error_code` is converted to `std::error_code` and then back