CPS SCHLCOLL data quality flags

Does anyone know why there are three data quality flags for SCHLCOLL in CPS, and how they might differ?
https://cps.ipums.org/cps-action/variables/SCHLCOLL#flags_section
Thanks, Bill

The IPUMS CPS variable SCHLCOLL is a combination of three responses from the CPS questionnaire. As noted on the SCHLCOLL description tab: “Interviewers first asked whether the person was enrolled in school during the previous week, then determined whether the person was attending high school or attending a college or university, and finally asked whether the person was a full-time or part-time student. In IPUMS-CPS, these responses are combined into the single variable SCHLCOLL.”

Each of these data quality flags relate to each of these three responses. QSCHCOL1 is the data quality flag for whether the person was enrolled in school during the previous week. QSCHCOL2 is the data quality flag for whether the person was attending high school or attending college or university. Finally, SCHCOL3 is the data quality flag for whether the person was a full-time or part-time student.

Makes perfect sense now, thanks Jeff.