Regarding the 3333 tie file:
  • A virtual check-in was created for the end of the day, because another
    gravity check-in point was used and 3333 wasn't revisited. To do this:
      – A Δ from datum value was calculated for the check-in used at the 
        end of the day:
          ○ station 6666
          ○ datum                          7363.498 mGal
          ○ end of day value             – 5507.589 mGal
          ○ Δ                            = 1855.909 mGal.
      – The Δ value was then subtracted from the datum of 3333 to create 
        a virtual check-in at the time of the 6666 check-in:
          ○ station 3333
          ○ datum                          7335.710 mGal
          ○ Δ                            – 1855.909 mGal        
          ○ virtual check-in             = 5479.801 mGal