Keyboards should have at least four rows (A through D); five rows (A through E) are preferred (see Figure 11.19).
Additional Information: Keyboard rows are designated by the letters “A,” “B,” “C,” “D,” and “E.” Row A is closest to the user; Row C is the center or home row.
Figure 11.9 shows a conventional keyboard with the row codes on the left. Additional rows of keys follow this same naming convention; for example, the first additional row would be labeled as Row F, and so forth.100
Figure 11.9 Basic QWERTY Layout On A Conventional Keyboard
(Source is Figure 6-1 in ANSI/HFES 100, 2007)