@hahagogomomo , What year did your DC apply, and did your Local Authority coordinate Sixth Form admissions? Most local authorities don't because, unlike for Reception and Year 7, they are not obliged to by law. Applicaa are trying to mimic the LA coordination process with their software.
As per Prh47bridge's post, clause 2.4 of the Admissions Code means that, at application stage, the schools should not have any information other than what is needed to make a decision on the application. When Local Authorities coordinate admissions for Reception and Year 7 they withhold the ranking info from schools. Each school only has the limited information that is provided on the LA application form and any Supplementary Information Form (SIF) they use. Their SIFs have to be published and consulted on as part of their admissions arrangements.
For uncoordinated Sixth Form admissions the school's own application form is the SIF. Yet most schools now use online forms which aren't published for consultation, but should be. Schools which use the Applicaa application process get preference ranking information for any applicants who apply for multiple schools, plus any other information included on the form (which schools can configure to include a range of common questions or their own questions). As well as the ranking issue, the Applicaa process is fundamentally flawed because it's designed to capture registration information at the same time as application information. Most forms I've seen therefore ask for things like ethnicity, SEN details, medical info and language info - none of which should be in an application form. Schools should only get that info after they have made offers, not before.
Most schools will hopefully administer their sixth form admissions in an ethical way, but as they're not being overseen by the LA, and are often not closely watched by their Governing body, there is plenty of evidence that illegal processes creep in, as shown in that Camden judgement.
The proprietors of the Applicaa software used to be teachers at Greenford High School, an LA-maintained foundation school in Ealing. Greenford's sixth form admissions policy is one of the worst I've seen, with multiple code breaches!