B737 NG FMC. Ref to barometric setting for FPA V/B and V/S on DES page.

[POL.777]

Scenario: setting a WPT and ALT on LSK 3R on DES page, you get the FPA V/B and V/S presented on LSK 4R.
Where does the FMC get the barometric pressure data from when calculating FPA, V/B and V/S as depicted on the DES page.
Is it from the forecast page, or the actual QNH setting on the PFD (or could it be referenced from STD?
Any reference to a Boeing manual would be highly appreciated.

[FCS Explorer]

as u might be above transition level my guess goes to DESC FORECAST page...

[POL.777]

Got the answer with a little help from a friend.
The FMC reads the baro setting from the PFD of the pilot with FD set to master. As far as I can see there is no reference to this in the FCOM.

Thanks.