Income-To-Poverty Ratio (PUMS) where does it comes from?

Hi,

I'm working with the PUMS, person and housing files (ACS-5year). I'm trying to find documentation about the income-to-poverty ratio (POVPIP).

  1. What is the poverty threshold used in the calculation for that variable?
  2. The poverty threshold used for the calculation it is determined from the ACS or another survey like the CPS?
  3. It is calculated nationwide or by geography as county, tract, PUMA?