Understanding Society User Support

Hi guys, in my research I need to classify people's educational levels. I find the derived variable of highest educational qualification (a_hiqual_dv) very useful. However, I cannot find detailed information on what the collapsed new categories of the derived variable "a_hiqual_dv" represent. For example, on its online documentation(https://www.understandingsociety.ac.uk/documentation/mainstage/dataset-documentation/wave/1/datafile/a_indresp/variable/a_hiqual_dv), only the value, absolute and relative frequency of the derived category "GCSE etc" are shown, but what does "GCSE etc" include? Because the new variable "a_hiqual_dv" is derived from more than one original variables(A_QFHIGH A_QFVOC1-A_QFVOC15), it is thus very difficult to figure it out by comparing the derived categories of "a_hiqual_dv" with the categories of the original variable, as the original categories are collected from 16 different variables. I do not find other helpful documents, either. So I was wondering if anybody is able to help me with this? My email is: syf08678@gmail.com , thank you!