Schematic diagram showing the construction of PSC graph with N number of primer sets. PS: Primer set, comprising a forward and a reverse primer; PSs is the plural form of PS. PSC: Primer set combination, a group of PSs; PSCs is the plural form of PSC. O: Represents a PS, different colors represent different PSs which come from different DNA template sequences. --: An edge connecting two PSs indicates that they are compatible to work together in one tube without any interference or competition to produce nonspecific amplicons. N: Represents the number of DNA template sequences in multiplex PCR.