| b_month | sample month |
| b_hhorig | sample origin |
| b_gor_dv | Government Office Region |
| b_istrtdatd | individual interview day |
| b_istrtdatm | individual interview month |
| b_istrtdaty | individual interview year |
| b_nsex | sex of respondent |
| b_nuroutc | nurse: final outcome code. if already entered, just press . if |
| b_rearef | nurse: enter reason for refusal... |
| b_lfout | lung function outcome. |
| b_nurdayd | nurse interview day |
| b_nurdaym | nurse interview month |
| b_nurdayy | nurse interview year |
| b_nurdayw | weekday of nurse interview |
| b_blddelay | number of days from taking blood sample to lab receiving blood |
| b_cati | cati outcome |
| b_elig | data release - eligibility variable |
| b_ethnic | ethnic group |
| b_ag16g10sel | age 16+ in ten year bands (at selection) |
| b_ag16g20sel | age 16+ in twenty year bands (at selection) |
| b_nuroutc_dv | nurse visit outcome derived |
| b_psu | primary sampling unit |
| b_strata | sampling strata |
| b_indnsus_li | w2 nurse visit inclusion weight |