# Microsoft.AspNetCore.Razor.TagHelpers

``` diff
 namespace Microsoft.AspNetCore.Razor.TagHelpers {
     public abstract class TagHelperContent : IHtmlContent, IHtmlContentBuilder, IHtmlContentContainer {
-        public TagHelperContent AppendFormat(IFormatProvider provider, string format, params object[] args);
+        public TagHelperContent AppendFormat(IFormatProvider provider, [StringSyntaxAttribute("CompositeFormat")] string format, params object[] args);
-        public TagHelperContent AppendFormat(string format, params object[] args);
+        public TagHelperContent AppendFormat([StringSyntaxAttribute("CompositeFormat")] string format, params object[] args);
     }
 }
```

