Symmetry of a Pfaffian system

It is a particular case of a symmetry of an EDS.
Given a Pfaffian system $\mathcal{P}=\mathcal{S}(\{{\alpha }_1,\dots ,{\alpha }_r\})$, a vector field $X$ is called a symmetry of $\mathcal{P}$ if

for every $\omega \in \mathcal{P}$. If the Pfaffian system is seen like a distribution (see dual description of the distribution) then $X$ corresponds to a symmetry of a distribution.