Combining keys, or nonescaping keys, are graphic character keys that do not cause an escapement, or cursor movement, when pressed. Repeating keys, on the other hand, will generate one graphic character if pressed; and if held down will keep on generating that character until the key is released. A key cannot be both repeating and combining at the same time.
To enter accented characters from a keyboard with a limited number of keys, you can use the combining function, which allows accents to appear independently of the base character that they change. When an accent is entered, the cursor does not move (escape) until the base character is entered. These combining characters (accents) can be anywhere on the keyboard.
Example: The keyboard shown earlier shows a combining key at position D-11 for the circumflex ^ and diaeresis ¨ accents. If you want to create the character û as in août via that keyboard, you must press the key at position D-11, and then the U key. The purpose of this layout is to put all the essential letters and accents for French on one group.
This layout could not be implemented with a keyboard logic that does not allow for support of a combining key at position D-11.
Allow any key that is used to enter a graphic character to be defined as a combining key or a repeating key at any level
The definition of a keyboard must allow the placement of combining characters anywhere within a keyboard group.
In addition, every level of every graphic key position must have an independently definable repeating function.