Compose maps

From The x3270 Wiki

Compose maps allow the input of accented or APL characters on keyboards that do not directly support them.

Pressing and releasing a key mapped to the Compose() action, then pressing two other keys in succession, inputs a character composed of those two keys.

The rules for composed characters are controlled by the current compose map. The default compose map is defined by the composeMap resource. A temporary compose map can also be enabled or disabled by the TemporaryComposeMap() action.