Hi Choi.
I recomend you think in this value in other way, just multiply the units * (actual cost - new standard)
48235 = 951 ( 300.72 - 250)
This is the value that roll up, exactly like other price difference because is needed in order to calculate the actual cost in month 08.
If you see the whole post (MR21 + CKMI) you can see the net value of BSX is the PRY value, i mean
bsx-MR21 + bsx-ckmi = pry = The price differenec between the actual and the new standard.
UMB-mr21 + umb-ckmi = 0
I think that UMB dont have relation with PRY, i mean is not part nor have a hiden value inside. UMB is just a temporary post, sort of trick that SAP create in order to comunicate previos and next month, but dont have relation with the PRY post.
the 50 is rounding difference, but this is other history....maybe topic of other blog...
You see in the end stock the "single level price determination, and dont have "inside" part of the UMB posted, nor create $ from nowhere.
Arturo.