Greek input method (GIM)
The Greek input method (GIM) is similar to the single-byte input method (SIM), but handles both Latin and Greek character sets, by providing two layers or states of keyboard mappings, which correspond to the two character sets.
The keyboard is initially in the Latin input state. However, if the left-shift key is pressed while the left-alt key is held down, the keyboard is put in the Greek input state. The keyboard can be returned to the Latin state by pressing the right-shift key, while the left-alt key is held down. These are locking shift keys, because the state is locked when they are pressed.
While in the Greek state, the input method recognizes the following diacritical characters and valid subsequent characters for diacritical composing as shown in the following table:
| Keysym | Valid Composing Characters |
|---|---|
| dead_acute | uppercase and lowercase: alpha, epsilon, eta, iota, omicron, upsilon, omega |
| dead_diaeresis | uppercase and lowercase: iota, upsilon |
| dead_accentdiaeresis | lowercase only: iota, upsilon |
In the Latin state, there are no composing diacriticals, and the keys shown in the table above are treated as simple graphic characters.
The Greek and Single-Byte Input Methods also differ in their handling of illegal diacritical composing sequences. In such cases, the GIM beeps and returns no characters. The SIM does not beep and returns both the diacritical character and a graphic character associated with the invalid key.