Automatic Selection (default)
With automatic selection, ENTER key is not required, the textbox value is automatically updated to match the current active descendant option. ENTER key will submit any associated form.
Autocomplete Off
Autocomplete List
Manual Selection
With manual selection, ENTER key is required to manually update the textbox with the value of the current active descendant (controlled via arrow keys). This means that an additional ENTER key press is required to submit any associated form.