diff --git a/README.md b/README.md
index 3972141..4d7eac0 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,9 @@ fn main() {
 ```
 
 3.  You need an INI file with your translations. Example with `translations.ini`:
+    Language translations are matched by `two lowercase letter` code (eg: `en`).
+    Localized language translations are identified by `two lowercase letter` code,
+    plus `hyphen`, plus `to letter localization` code (eg: `en-gb`).
 
 ```
 [app_ruin_the_band]
diff --git a/src/lib.rs b/src/lib.rs
index c8e0169..d6dcd13 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -22,6 +22,9 @@
 //! ```
 //!
 //! 3.  You need an INI file with your translations. Example with `translations.ini`:
+//!     Language translations are matched by `two lowercase letter` code (eg: `en`).
+//!     Localized language translations are identified by `two lowercase letter` code,
+//!     plus `hyphen`, plus `to letter localization` code (eg: `en-gb`).
 //!
 //! ```text
 //! [app_ruin_the_band]