I have come across the term group-writing (originally in a comment on this question but also elsewhere), apparently referring to a system the Egyptians used for transliterating foreign names. However, searching online has been surprisingly unhelpful in terms of finding reference material to understand what group-writing actually is; I guess because of a combination of obscurity and changing terminology.
I am looking for sources, preferably available freely online (I have JSTOR access but it is somewhat limited, and I'm not a member of an academic libraries), to understand what group-writing is. I'm a beginner when it comes to Egyptian but I'm comfortable reading technical material and just letting the extraneous detail wash over me.