The number of local contacts (NLC) is a novel index derived from the fraction of local contact. The weighted implementation of this index in ProtDCal is as follow:
Where wij is a weighting factor equal to the product of any of the residue's properties listed as property based indices for each residue involved in the contact plus the topological distance between the pair of residues, additionally it can be fixed at 1 in the case that not weight it wants to be used.