AWS  CLAUSE 6.12.1
(5) Isolated discontinuities such as a cluster of rounded indications, having a sum of their greatest dimensions exceeding the maximum size single discontinuity allowed in Figure 6.1. The minimum clearance to another cluster or an elongated or rounded discontinuity or to an edge or end of an intersecting weld shall be three times the greatest dimension of the larger of the discontinuities being considered.

Please clarify the above statement. How we will take the sum of porosity in a cluster. I understood that the porosity having length more than 2.5 mm shall be added and evaluate accordingly. If not what is the minimum size of porosity to be considered in a cluster for taking the sum of all porosities  in the cluster.