what is relinquished property equity on a 1031 exchange

30 years ago I bought a rental propety

20 years  I did a qualified 1031 exchange

Now I am selling the 2nd building

On my exchange agreement from 20 years ago there is a $ amount called  "Relinquished Property Equity" 

Is this  amount the basis that I should use going into the calculation for the 2nd building? 

I assume that I subtract the depreciation on the first building from this relinquished property amount / basis  before calculating building 2?