Understanding Society User Support

Hi there,

I wanted to double-check which further data is available under the Secure Access level (SN 6676). From the info online, I understand it's mostly location-based data and full birth date info. Are there any other types or is it possible to see a full list somewhere?
I've found some useful documents comparing EUL and SL variables but I haven't found anything similar for data available through secure access (https://doc.ukdataservice.ac.uk/doc/6676/mrdoc/pdf/6676_eul_vs_sl_variable_differences.pdf).

I'm interested in citizenship, immigration-related and household income data. From what I've been able to find online it sounds like all of this is either on the EUL or SL for more granular info e.g. country of citizenship. Is that right?

One thing that was slightly confusing was that the variable search says that citzn_code and citzn2_code are both "only available in the Special Licence (SN 6931) and Secure Access (SN 6676) datasets". But does that mean that the SA version is different from the SL version?

I also had a separate query about the questions asked of the IEMB households in subsequent waves: am I right in thinking that the questions, which weren't asked of the IEMB sample in W6 e.g. youth questionnaire, material deprivation, some employment histories questions etc. would have been asked of these households in subsequent waves i.e. every subsequent year for the youth questionnaire and Waves 8, 10 etc. for the material deprivation questions.

Thanks so much!
Ilona