I based my speculation on some observations I had made on some of my own systems when I implemented dir_index. It so happens that, on that system at least, a "find /foo -print" returns the filenames in sorted order. Unfortunately, it isn't true on another system that I just checked. So now I will go and stand in the corner :(
:)
Anyway, your tip gave me some precious direction. Monday I will investigate and then report. Thank you!