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Most works on seniority in nuclear physics involve particles of one kind-only proton or only neutrons. However, we had previously observed that in a single j shell calculation for ${}^{48}$Cr (four ${\text{f}}_{7∕2}$ protons and 4 ${\text{f}}_{7∕2}$ neutrons), a quantum number emerges that can be assigned to a given wave function, namely $\mathrm{\text{SEN}}={(-1)}^{((\text{v}\text{p}+\text{v}\text{n})∕2)}$. A given column vector will either have $\mathrm{\text{SEN}}=+1$ or $\mathrm{\text{SEN}}=-1$. This is exclusive to mid-shell nuclei. But there is more. There is another quantum number common to all $N=Z$ nuclei ${}^{44}$Ti, ${}^{46}$V and ${}^{48}$Cr. This leads to additional zeros in the components of the column vectors.