Understanding Society User Support

Dear Sir / Madam

Where can we find information on whether an individual is born outside the UK for all adult individual respondents at wave 2? We have seen this data for those present at wave 1. We realise that for those that took part in wave 1 they will not be asked this again, and similarly BHPS participants will previously have been asked this. Therefore we had expected to have to use data from the xwavedat record when analysing wave 2 onwards. However when we look at the variable UKBORN from the xwavedat file from the most recent data deposit appears to have missing data for over 40,000 individuals. Please advise how to construct "uk born / non uk born" for all respondents. Thanks.