diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 8115371..a44b6f6 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2025 Mar 10
+*syntax.txt*	For Vim version 9.1.  Last change: 2025 Mar 15
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -1286,6 +1286,21 @@
 startup vimrc: >
    :let filetype_w = "cweb"
 
+CSHARP							 *cs.vim* *ft-cs-syntax*
+
+C# raw string literals may use any number of quote marks to encapsulate the
+block, and raw interpolated string literals may use any number of braces to
+encapsulate the interpolation, e.g. >
+
+    $$$""""Hello {{{name}}}""""
+<
+By default, Vim highlights 3-8 quote marks, and 1-8 interpolation braces.
+The maximum numbers of quotes and braces recognized can configured using the
+following variables:
+
+    Variable					Default ~
+    g:cs_raw_string_quote_count			8
+    g:cs_raw_string_interpolation_brace_count	8
 
 DART						*dart.vim* *ft-dart-syntax*