llSetKeyframedMotion([<-0.090044, -0.109650, 0.764997, 0.628211>,5,<-0.087154, -0.151111, 0.378011, 0.909218>,5],[KFM_DATA,KFM_ROTATION,KFM_MODE,KFM_PING_PONG]);

Does not produce the same result as:

llSetKeyframedMotion([ZERO_VECTOR, <-0.090044, -0.109650, 0.764997, 0.628211>,5,ZERO_VECTOR,<-0.087154, -0.151111, 0.378011, 0.909218>,5],[KFM_MODE,KFM_PING_PONG]);

KFM_FORWARD, KFM_REVERSE, and KFM_LOOP all behave the same in this comparison. The deviation seems isolated to KFM_PING_PONG. I haven't figured out if one is correct and the other is not, or if both are broken.