The characteristic function of $X$ is the D992: Function
\begin{equation}
\mathbb{R}^N \to \mathbb{C}, \quad
\xi \mapsto \mathbb{E}_{\mathbb{P}}(e^{i t \cdot X})
\end{equation}
The characteristic function of $X$ is the D992: Function
\begin{equation}
\mathbb{R}^N \to \mathbb{C}, \quad
\xi \mapsto \int_{\Omega} e^{i t \cdot X} \, d \mathbb{P}
\end{equation}