2.2.3-9 Consistent Logic for Double Keying

If double (control/shift) keying is used, the logical relation between shifted and unshifted functions should be consistent from one key to another.

Additional Information:
Consistency in the underlying logic for double keying will help a user to learn the functions associated with different keys. For example, one consistent logic might be that shifted and unshifted functions are opposite, so that if a particular key moves the cursor forward, then that key, when shifted, would move the cursor backward. Another possible logic might be that shifted and unshifted functions are related by degree, so that if a particular key deletes a single displayed character, then that key, when shifted, would delete a word.