Understanding Society User Support

Hi there

I am trying to carry out a set of analyses for specific industry groups but I find that, of the 23,177 sample cases in the c_indresp dataset for Wave 3 who are employees, 17,381 have jbsic07_cc missing. Of these 17,381 cases, 17,270 have jbsic07chk equal to 1 (Yes). According to the questionnaire documentation (https://www.understandingsociety.ac.uk/documentation/mainstage/dataset-documentation/wave/3/questionnaire-module/currentemployment_w3), this means that their industry classification from a previous wave (ff_JBSIC07) still applies. However this variable doesn't appear to be on the dataset. Is there a derived variable on the dataset that enables me to obtain the industry grouping for all current employment spells, regardless of whether the value has changed since the last wave? If not, is the only way of obtaining an industry classification to cycle through all previous waves picking up previous values for <w>_jbsic07? If I have to do this, do I need to go through all waves of the BHPS or only the waves of Understanding Society. Alternatively, if this derived variable doesn't exist on the Wave 3 data, does it exist on Wave 4 as I could switch my analysis to that wave if helpful.

Thank you

Ashwin Kumar