Accessibility users may press the caps lock key accidentally whilst entering data.
The status of the caps lock key may affect data entry within some applications, causing capital letters to be entered in place of lowercase letters, or vice-versa. A user with low literacy skills may not notice that they are typing in capitals, and all subsequent capitalization from pressing the caps lock key may be wrong.
It is recommended that application programs ignore the state of the caps lock key, when the key should not be effective.
If the application program is affected by the caps lock key status during data entry, then the input cursor should change shape to indicate that the caps lock key is in effect. A flashing capital letter C makes a good caps lock status indicator.
If the caps lock key affects non data entry aspects of the application program, then an on screen indicator should be used to make it clear that the caps lock key is effective.
Caps lock indicator lamp Edit
Beware of bad keyboards! The keyboard should be so designed so that the placement of the caps lock indicator lamp is on the caps lock key itself. Some badly designed keyboards have the caps lock indicator lamp in the top right hand corner away from the caps lock key. This causes a problem for accessibility users who do not notice the status of the lamp.