I wonder about the distinctions legally given machine based tools and context insensitivity and what separates identical results.

If one had a list of proxies for every ethnicity and individually assigned all but one would it qualify as legal targeting or illegal discrimination?

Would this format derived from US ethnicity census be legal: [x] White [] Black or African American [x] American Indian or Alaska Native [x] Asian or Native Hawaiian or Other Pacific Islander

but a query of 'exclude "Black or African American"' be considered illegal even if they both map to an abbreviated form of hexadecimal B? Although it could be argued that by making the discriminators have to work harder to figure out how to exercise bigotry in advertising is a reasonable baseline.

The spirit of the law is clear but I wonder about the mechanics of it for avoiding all of the gross loopholes and technicalities and enforceability. Just advertising home listings in 'Farmer's Weekly' (for sake of example assuming it has an overwhelmingly white subscriber base) for selling an exurban house wouldn't prove discriminatory intent and short of memos giving racist directives to the marketing department being released.