Details codebooks for S1901, S1902, and S1903?

Hello All,

I am new to this forum, so apologies if my question has already been answered. I'm working at the county level, and I want data on incomes, income distributions, and incomes/income distributions by race/ethnicity, so I have the S1901-S1903 datasets. Do codebooks exist to explain the variables? For example, S1902_C01_0028E is "Estimate!!Number!!PER CAPITA INCOME BY RACE AND HISPANIC OR LATINO ORIGIN!!Total population!!White alone, not Hispanic or Latino," but is this pre-tax or post-tax? What income streams are included/excluded? Is per capita income evenly distributed to all adult members of a household? As another example, I have determined that S1901_C01_002E through S1901_C01_011E provides percentile distributions of various household income categories, but it would be good if the ACS stated that clearly in a codebook.

Thanks for any help you can provide