+ L(\Lambda_1) + L(\Lambda_{\ell-1}) + L(\Lambda_{\ell}).$$ More precisely, $$L(\Lambda_0) \cong V_Q, \quad L(\Lambda_1) \cong e^{\omega_1} V_Q = e^{\omega}V_Q, \quad L({\Lambda_{\ell-1}}) \cong V_Q e^{\omega_{\ell-1}}, \quad L({\Lambda_{\ell}}) \cong V_Q e^{\omega_{\ell}}$$ with highest weight vectors $v_{\Lambda_0} = e^{\omega_0} = {\ensuremath{{\bf 1}}}, \ v_{\Lambda_1} = e^{\omega_1}, \ v_{{\Lambda_{\ell-1}}} = e^{\omega_{\ell-1}}$ and $v_{{\Lambda_{\ell}}} = e^{\omega_{\ell}}$ respectively. The space $V_Q$ has the structure of the vertex operator algebra (VOA) and $V_P$ is a module for this algebra (cf. [@FLM], [@DL]).

Vertex operators $Y(e^{\lambda},z), \ \lambda \in P$ satisfy generalized Jacobi identity. We shall use the intertwining operators: $$\mathcal{Y}: V_P \longrightarrow (\textrm{End} V_P) \{ z \},$$ $$v \mapsto \mathcal{Y}(v,z),$$ defined for $v=v^{*}\otimes e^{\mu} \in V_P$ as: $$\begin{aligned}
 \label{vert_def}
\mathcal{Y}(v,z) = Y(v,z)e^{i \pi \mu}c(\cdot, \mu).\end{aligned}$$ Operators $Y(e^{\lambda},z_1)$ and $\mathcal{Y}(e^{\mu}, z_2)$, $\mu, \lambda \in P$, satisfy the ordinary Jacobi identity and restrictions of $\mathcal{Y}(e^{\mu},z)$ are in fact maps

$$\begin{aligned}
\label{intop}
\mathcal{Y}(e^{\mu},z) : L(\Lambda_i) \longrightarrow L(\Lambda_j)\end{aligned}$$

if $\mu + \omega_i \equiv \omega_j \ \textrm{mod} \ Q.$ This restrictions give us the intertwining operators between standard modules of level 1 ([@DL]).

The commutator formula ([@DL]) $$\begin{aligned}
\label{komutator}
[ Y(e^{\gamma},z_1), \mathcal{Y}(e^{\mu}, z_2) ] = \textrm{Res}  \end{aligned}$$ and the relation $$\begin{aligned}
\label{formula}
\mathcal{Y}(e^{\lambda}, z_0) e^{\nu} = Ce^{\lambda + \nu}z_0^{\langle \lambda, \nu \rangle} + 