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 # codenames
 The codenames for NXD airliners
+
+## Class Letter
+|       Letter       | Role                     | Number Range | Example |
+| :----------------: | :----------------------- | :----------- | :------ |
+|        **E**       | Economy / Glider         | 100–300      | E220    |
+|        **A**       | Airliner / Transport     | 300–500      | A350    |
+|        **F**       | Fighter / Performance    | 400–900      | F780    |
+|        **S**       | Luxury / Executive       | 500–700      | S650    |
+
+## Number range
+|  Range  | Meaning                          | Typical Use                        |
+| :-----: | :------------------------------- | :--------------------------------- |
+| **100** | Small / trainer class            | Entry level, single-engine gliders |
+| **200** | Light / compact                  | Small electric planes              |
+| **300** | Medium / balanced                | Light airliners or medium range    |
+| **400** | Mid-heavy / higher power         | Large airliners or light fighters  |
+| **500** | Large / advanced                 | Wide-body jets or heavy fighters   |
+| **600** | Flagship / specialized           | Supersonic or long-range military  |
+| **900** | Experimental / tech demonstrator | Cutting-edge prototype             |
+
+## Generation
+**`N1` `N2` `N3`** ..