| c_month | sample month |
| c_hhorig | sample origin |
| c_gor_dv | Government Office Region |
| c_istrtdatd | individual interview day |
| c_istrtdatm | individual interview month |
| c_istrtdaty | individual interview year |
| c_nuroutc | nurse: final outcome code. if already entered, just press . if |
| c_rearef | nurse: enter reason for refusal... |
| c_lfout | lung function outcome. |
| c_nurdayd | nurse interview day |
| c_nurdaym | nurse interview month |
| c_nurdayy | nurse interview year |
| c_nurdayw | weekday of nurse interview |
| c_blddelay | number of days from taking blood sample to lab receiving blood |
| c_cati | cati outcome |
| c_elig | data release - eligibility variable |
| c_ethnic | ethnic group |
| c_ag16g10sel | age 16+ in ten year bands (at selection) |
| c_ag16g20sel | age 16+ in twenty year bands (at selection) |
| c_nuroutc_dv | nurse visit outcome derived |