A mnemonic is an alphanumeric character, which indicates the key to press to activate a command or navigate to a component.
There are regular and numeric mnemonics.
Regular mnemonics are used inside the text. The mnemonic is underlined in this case to be distinguishable.
In a control:
In a menu:
Activate the control by pressing the mnemonic with:
Alt modifier key on Windows/Linux
Ctrl+Alt modifier keys on macOS.
Numeric mnemonics are used as the first numeric character of an action in a popup:
Invoke the action by pressing the corresponding number key.
When to use
Specify mnemonics wherever possible in menus and controls. Mnemonics make the functionality more usable for power users who interact through the keyboard. Moreover, mnemonics make the functionality accessible for users with disabilities.
If there are many actions and/or controls, and it is not possible to assign mnemonics for all of them:
Provide mnemonics for the most frequently used actions/controls.
Provide mnemonics for group headers for quick navigation to the first element of the group.
Note: The rules for using numeric mnemonics in popups are under discussion. Contact us if you have questions.
How to use
Make mnemonics in the label discoverable, they must be easy to find:
Use letters at the beginning of the first or second word of the label.
Use letters with wide widths, such as w, m, and capital letters.
Avoid using letters that are difficult to see when they are assigned to underlined keys. These letters include:
Letters with descenders, such as g, j, p, q, or y.
Letters next to a letter with a descender.
Letters that are only one pixel wide, such as i or l.
Make it easy to remember for the most frequently used actions:
Use standard Windows mnemonic if any. For example, Properties, Rename, Delete, Cut, Copy, Paste, Exit, etc. Note that Windows users are more likely to form habits for mnemonics as mnemonics are not that common on macOS or Linux.
Do not use silent letters. For example, Design, Column, etc.
Do not assign mnemonics to the default or Cancel buttons. The default button is typically assigned to the ENTER key, and Cancel is assigned to the ESC key.
Do not use the same mnemonic letter twice in the same window; duplicated mnemonics confuse users. If you need to assign a new mnemonic in an existing context, check that it's not already taken. If it is, prioritize the mnemonic for the more frequently used action.
