The standard cursor movement keys on the TI-99/4, /4A and apparently /8 were Function + E (for up), S (for left), D (for right), and X (for down). These keys were also often used (without needing the function key) for games.
WordStar on CP/M used the same keys, albeit using Control rather than Function (as Function was a somewhat specific key to the TI keyboard). A number of other CP/M and early DOS applications copied the WordStar combinations, so they were quite common for a while.
Was this coincidental, did one of these copy the other, or did they both derive from some common older source that I'm not aware of?