What type of crystal defect is indicated in the diagram below?

$\begin{array}{l}{\mathrm{Na}}^{+}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Cl}}^{-}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Na}}^{+}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Cl}}^{-}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Na}}^{+}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Cl}}^{-}\\ {\mathrm{Cl}}^{-}\hspace{0.25em} \hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\mathrm{◻}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} {\mathrm{Cl}}^{-}\hspace{0.25em}\hspace{0.25em}{\mathrm{Na}}^{+}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\mathrm{◻}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} {\mathrm{Na}}^{+}\\ {\mathrm{Na}}^{+}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Cl}}^{-}\hspace{0.25em} \mathrm{◻}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} {\mathrm{Cl}}^{-}\hspace{0.25em}\hspace{0.25em} {\mathrm{Na}}^{+} {\mathrm{Cl}}^{-}\\ {\mathrm{Cl}}^{-}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Na}}^{+}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Cl}}^{-}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}{\mathrm{Na}}^{+}\hspace{0.25em} \hspace{0.25em}\mathrm{◻}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em} {\mathrm{Na}}^{+}\end{array}$

In the diagram, the Schottky defect is represented by an equal number of missing sodium cations and chloride anion.
A cation or anion departs its normal site and assumes an interstitial place in a Frenkel defect.