Is there a more detailed definition of variables under the PCT_RACE category, such as PCT_WHITE or PCT_HISPANIC?

Question

The College Scorecard Data Dictionary simply describes the variables as the percent of the population from the students' zip codes that are of that race, of the students in the earnings cohort. Is this the average over all of the zip codes? The earnings cohort refers to earnings after college, so is this considering a student's zip code prior to or post-graduation? Any help is appreciated