Input and Controls:

1. Allow connection, substitution, or addition of alternative input components (that is, keyboards, pointing devices, and so on)
2. Make all controls operable from keyboard
3. Have all controls mounted on the front of the device (that is, facing the user)
4. Use push buttons primarily
5. Use concave buttons (especially where sustained force is required)
6. Avoid twisting motions (instead, use push buttons or edge controls)
7. Minimize the force required for operation (that is, less than 2 Newtons)
8. Make all controls operable with one hand (preferably with one finger or assistive pointing device)
9. Avoid capacitance-based controls (that is, controls do not require skin contact)
10. Use functional grouping or layout of controls
11. Make controls tactually discernible
12. Make the state of non-momentary controls tactually discernible
13. Have tactile and audible actuation feedback for controls
14. Avoid keys that cannot be read or simulated by software
15. Maximize sizes of controls within the space available
16. Make distance between controls sufficient for tactile and visual discrimination
17. Manufacture input guards or provide mounting for guards
18. Provide stable keyboards