The acronyms “IBC” and “IBCs” are the same IBC simply in singular and plural form.
“Composite IBCs” referred to in 188.8.131.52.2 Step 6 is one of those IBCs consisting of an outer packaging (say steel material) and an inner receptacle (say plastic material) so constructed that the inner receptacle and the outer packaging form an integral packaging. It is different from the Flexible IBC dealt in Figure 8.1.N.
Flexible IBC in DGD Figure 8.1.N has a code 13H2. Per Table 6.8.A, this is an IBC made of plastic material to contain solids, and the filling and discharging are done by gravity. Furthermore per Table 6.8.B, it is made of woven plastic with coating. It is different from the Composite IBC dealt in 184.108.40.206.2 Step 6, the latter will carry a code 11HZ1 or 11HZ2 or 21HZ2 per Table 6.8.B.