isotropic submanifold

If $(M,\omega )$ is a symplectic manifold, then a submanifold $L\subset M$ is isotropic if thesymplectic form vanishes on the tangent space of $L$, that is, $\omega (v_1,v_2)=0$ for all$v_1,v_2\in T_{\mathrm{\ell }}L$ for all $\mathrm{\ell }\in L$.