According to AARC document AARC-JRA1.4a-201710

<GROUP> is the name of a Virtual Organisation (VO), research collaboration or a top level arbitrary group. Group

names MUST be unique within a given namespace;

In COmanage we can not define the type of the CoDepartment that encapsulates the relevant information of a COU. This creates limitations when we want to apply rules for certain types of COUs since we can not distinguish amongst them.