swap_ctrl_keys
The option documentation is properly formatted yet
Description: "Swap left and right CTRL keys" Default: 0 Example: 1 Since: 2.1.4 Type: boolean
This option can be used to swap left and right CTRL keys before the keys are processed. This makes it possibly to use the left key for emulated joystick fire button, for example.
Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/swap_ctrl_keys