Scheme of cold gas origin classification. After selecting cold gas particles in the CGM (hence excluding gas in the disk of the main galaxy and gas in satellites) at a chosen redshift z, their origin was discovered by tracking back in the previous snapshots of the simulation. The green boxes represent location criteria: particles coming from the disk, coming from a satellite, or always present in the CGM. In the red boxes are shown particles in the CGM that have always been cold (hence in cold inflow since they must have been accreted directly in cold phase at some moment in the galaxy evolution) and particles that cooled down from above the threshold temperature (T = 3 × 10⁴ K). Finally shown are static particles (radial velocity |v_r|< 50 km s⁻¹) and particles with inflowing or outflowing velocity.