diff --git a/src/client/connection/request/titan.rs b/src/client/connection/request/titan.rs
index 70b9376..de181a2 100644
--- a/src/client/connection/request/titan.rs
+++ b/src/client/connection/request/titan.rs
@@ -1,9 +1,15 @@
 use glib::{Bytes, Uri, UriHideFlags};
 
-/// [Titan](gemini://transjovian.org/titan/page/The%20Titan%20Specification) protocol enum object for `Request`
+/// Optionally use this value by default for the text input
+pub const DEFAULT_MIME: &str = "text/gemini";
+
+/// Formatted [Titan](gemini://transjovian.org/titan/page/The%20Titan%20Specification) `Request`
 pub struct Titan {
     pub uri: Uri,
     pub data: Bytes,
+    /// MIME type is optional argument by Titan protocol specification,
+    /// but server MAY reject the request without `mime` value provided
+    /// * see also `DEFAULT_MIME`
     pub mime: Option<String>,
     pub token: Option<String>,
 }