t $$\begin{aligned} {\it l}_u\,\mathfrak{U} &=& T\,{\it l}_u\mathfrak{s} +E\wedge{\it l}_u P +B\wedge{\it l}_u M\nonumber\\ &&+{\Sigma _{\alpha}}_{\bot}^{\rm matt}\wedge{\cal \L\/}_u\underline{\vartheta}^\alpha -\underline{\Sigma}^{\rm matt}_\alpha\,{\cal \L\/}_u u^\alpha\nonumber\\ &&+\Gamma _{\bot}^{\alpha\beta}\bigl(\,\vartheta _{[\alpha}\wedge\Sigma ^{\rm matt}_{\beta ]}\bigr)_{\bot}\,.\label{