diff --git a/rups/src/proto/client.rs b/rups/src/proto/client.rs
new file mode 100644
index 0000000..0a8ceb1
--- /dev/null
+++ b/rups/src/proto/client.rs
@@ -0,0 +1,35 @@
+use crate::proto::impl_sentences;
+
+impl_sentences! {
+    /// Server responds with the number of prior logins to the given `ups_name` device.
+    RespondNumLogins (
+        {
+            0: NumLogins,
+            1: Arg,
+            2: Arg,
+            3: EOL,
+        },
+        {
+            /// The name of the UPS device.
+            1: ups_name,
+            /// The number of logins to the UPS device.
+            2: num_logins,
+        }
+    ),
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Sentences;
+    use crate::proto::test_encode_decode;
+    #[test]
+    fn test_encode_decode() {
+        test_encode_decode!(
+            ["NUMLOGINS", "nutdev", "42"] <=>
+            Sentences::RespondNumLogins {
+                ups_name: "nutdev".into(),
+                num_logins: "42".into(),
+            }
+        );
+    }
+}
diff --git a/rups/src/proto/mod.rs b/rups/src/proto/mod.rs
index 846092f..7089071 100644
--- a/rups/src/proto/mod.rs
+++ b/rups/src/proto/mod.rs
@@ -1,3 +1,8 @@
+/// Client-bound protocol implementation.
+///
+/// "Client-bound" implies commands RECEIVED and DECODED by the client. The server implementation
+/// must use the same messages to ENCODE and SEND.
+pub mod client;
 /// Server-bound protocol implementation.
 ///
 /// "Server-bound" implies commands RECEIVED and DECODED by the server. The client implementation