Along the perimeter of all volumes (base, shoulder straps, main volumes) and pockets you see a sewn strong braid (soutache), divided into 20 mm cells (figure 1 in the photo). Pockets and volumes are attached to the base and between each other by knots (3 in the photo), which are instantly threaded into the cells and hold tight. Fasteners - chest ties, holders of tracking poles, ties, etc. - are attached directly to the cells or engages with them through such plastic stoppers (2 in the photo).
The described system allows fastening individual parts (modules) quickly, flexibly and reliably, and also quickly reconfigure the backpack if necessary.
Please also see the video