If you look on PPL e-exams on the CAA website, they have the learning objectives as a series of documents labelled CAP2090A thru J to cover the 9 subjects.
Looking at the 061 section I can see the first five LOs are straight from EASA, and they have added the relevant Radio Nav ones as an additional 5.
Navigation should be 060, with Gen Nav as 061 and Radio Nav 062.
i can see a lot of ATPL tripe in the objectives, such as chart properties and working out wind velocity using the CrP-5. I trust that the exams just focus on the VFR chart symbols and airspace, how to work out heading and ground speed, and converting volume to weight?
The LO in question is with regards to GPS operation. Since you are reading from a device which does the job, what do you need to know other than it triangulates time based signals, is accurate to 30 metres laterally, and is not line of sight limited?