A non-zero value would violate $\mathit CPT$ invariance in decay amplitudes with $\Delta \mathit S$ ${}\not=$ $\Delta \mathit Q$. x$_{-}$, used here to define Re(x$_{-}$), and x$_{+}$, used below in the $\Delta \mathit S$ = $\Delta \mathit Q$ section are the following combinations of ${{\mathit K}_{{e3}}}$ decay amplitudes: x$_{\pm{}}$ = ${1\over 2}{ A( {{\overline{\mathit K}}^{0}} \rightarrow {{\mathit \pi}^{-}} {{\mathit e}^{+}} {{\mathit \nu}_{{e}}} )\over A( {{\mathit K}^{0}} \rightarrow {{\mathit \pi}^{-}} {{\mathit e}^{+}} {{\mathit \nu}_{{e}}} )}$ $\pm{}$ ${ A( {{\mathit K}^{0}} \rightarrow {{\mathit \pi}^{+}} {{\mathit e}^{-}} {{\overline{\mathit \nu}}_{{e}}} ){}^{*}\over A( {{\overline{\mathit K}}^{0}} \rightarrow {{\mathit \pi}^{+}} {{\mathit e}^{-}} {{\overline{\mathit \nu}}_{{e}}} ){}^{*}}$ .