Unfortunately in that chapter there is no mention about MMS,
by the way the top of "amber foot" is independent from values inserted on the FMS and it is "self calculated" from the aircraft from 400' and above.
Boeing do this (similar to Airbus) in order to guarantee the margin on lower speed regardless of weight data inserted on FMS that sometimes are wrong.
What i should like to know is the source of the MMS, certainly the Angle of Attack, the air density & temp, the stabilizer trim settings and so on.
Anyone knows more about it?