# System.Text

``` diff
 namespace System.Text {
     public sealed class StringBuilder : ISerializable {
-        public StringBuilder AppendFormat(IFormatProvider? provider, string format, object? arg0);
+        public StringBuilder AppendFormat(IFormatProvider? provider, [StringSyntaxAttribute("CompositeFormat")] string format, object? arg0);
-        public StringBuilder AppendFormat(IFormatProvider? provider, string format, object? arg0, object? arg1);
+        public StringBuilder AppendFormat(IFormatProvider? provider, [StringSyntaxAttribute("CompositeFormat")] string format, object? arg0, object? arg1);
-        public StringBuilder AppendFormat(IFormatProvider? provider, string format, object? arg0, object? arg1, object? arg2);
+        public StringBuilder AppendFormat(IFormatProvider? provider, [StringSyntaxAttribute("CompositeFormat")] string format, object? arg0, object? arg1, object? arg2);
-        public StringBuilder AppendFormat(IFormatProvider? provider, string format, params object?[] args);
+        public StringBuilder AppendFormat(IFormatProvider? provider, [StringSyntaxAttribute("CompositeFormat")] string format, params object?[] args);
-        public StringBuilder AppendFormat(string format, object? arg0);
+        public StringBuilder AppendFormat([StringSyntaxAttribute("CompositeFormat")] string format, object? arg0);
-        public StringBuilder AppendFormat(string format, object? arg0, object? arg1);
+        public StringBuilder AppendFormat([StringSyntaxAttribute("CompositeFormat")] string format, object? arg0, object? arg1);
-        public StringBuilder AppendFormat(string format, object? arg0, object? arg1, object? arg2);
+        public StringBuilder AppendFormat([StringSyntaxAttribute("CompositeFormat")] string format, object? arg0, object? arg1, object? arg2);
-        public StringBuilder AppendFormat(string format, params object?[] args);
+        public StringBuilder AppendFormat([StringSyntaxAttribute("CompositeFormat")] string format, params object?[] args);
     }
 }
```

