From 6945b6a25fc17f0e890263f70f410035fd926649 Mon Sep 17 00:00:00 2001
From: MeexReay <meexreay@gmail.com>
Date: Sun, 22 Jun 2025 20:45:26 +0300
Subject: [PATCH] extensions

---
 EXTENSIONS.md | 34 ++++++++++++++++++++++++++++++++++
 README.md     |  2 +-
 2 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 EXTENSIONS.md

diff --git a/EXTENSIONS.md b/EXTENSIONS.md
new file mode 100644
index 0000000..8f86d56
--- /dev/null
+++ b/EXTENSIONS.md
@@ -0,0 +1,34 @@
+# Extensions
+
+Over time, as various clients and servers for RAC were developed, users introduced their own protocol extensions. These additions were created independently of Mr. Sugoma and are designed to enhance the protocol's capabilities while maintaining compatibility with existing RAC versions.
+
+## Server info packet
+
+Client sends:
+
+- Byte `0x69`
+
+Server sends:
+
+- (nothing or closes socket if server doesn't support this feature)
+- Protocol version:
+    - Byte `0x01` for RACv1 
+    - Byte `0x02` for RACv1.99
+    - Byte `0x03` for RACv2
+- Server name
+
+## User agents
+
+User agents in RAC is the way how to get know from what client the message was sent. It works by just checking the message text throught regex.
+
+Here are listed the most common clients, and their common names colors in the chat.
+
+| Client        | Format        | Regex     | Color     |
+|    :----:     |    :----:     |    :----: |  :----:   |
+| [bRAC](https://github.com/MeexReay/bRAC) | 리㹰<{name}> {text} | `\uB9AC\u3E70<(.*?)> (.*)` | green
+| [CRAB](https://gitea.bedohswe.eu.org/pixtaded/crab) | ═══<{name}> {text} | `\u2550\u2550\u2550<(.*?)> (.*)` | light red
+| [Mefidroniy](https://github.com/OctoBanon-Main/mefedroniy-client) | °ʘ<{name}> {text} | `\u00B0\u0298<(.*?)> (.*)` | light magenta
+| [cRACk](https://github.com/pansangg/cRACk) | ⁂<{name}> {text} | `\u2042<(.*?)> (.*)` | gold
+| [Snowdrop](https://github.com/Forbirdden/Snowdrop) | ඞ<{name}> {text} | `\u0D9E<(.*?)> (.*)` | light green
+| clRAC | <{name}> {text} | `<(.*?)> (.*)` | cyan
+
diff --git a/README.md b/README.md
index 17b7da9..143a8f4 100644
--- a/README.md
+++ b/README.md
@@ -56,7 +56,7 @@ The following documents cover the structure, behavior, and expectations of RAC a
 - [RACv1.99.x](RACv1.99.md)
 - [RACv2.0](RACv2.md)
 - [WRACv2.0](WRAC.md)
-- [Users additions](USERS_ADDITIONS.md)
+- [Extensions](USERS_ADDITIONS.md)
 
 [^4]: "_Про RAC 1 вообще забудь, это днище, его юзать нельзя._" - Mr. Sugoma