The 2018 form instructions are incomplete at this time.  

IRS draft form and instructions: https://www.irs.gov/pub/irs-dft/i3800--dft.pdf

Once complete, we can review the flow of these entries in comparison to the final Form 3800 instructions for 2018 which will be listed on IRS here: https://taxmap.irs.gov/taxmap/forms/formtoc.htm  (currently displaying 2017 information)