I didn’t say a “complete” list, just a “reasonable” list. MTH has added additional soft keys to later PS3 engines but hasn’t updated that list.
Anyway, to see what soft keys your particular engine has,
Use S5 (picture 1) to scroll until you see “more” (picture 2) and then push S4 to select it. You will then see the list of all soft keys your engine has (picture 3). In this case, number 8 corresponds to SXS which is XING SIGNAL. Scroll up or down thru the entire list.