  Thurston defined invariant laminations, i.e. collections of chords of the
unit circle $S^1$ (called \emph{leaves}) that are pairwise disjoint inside the
open unit disk and satisfy a few dynamical properties. To be directly
associated to a polynomial, a lamination has to be generated by an equivalence
relation with specific properties on $S^1$; then it is called a
\emph{q-lamination}. Since not all laminations are q-laminations, then from the
point of view of studying polynomials the most interesting are those of them
which are limits of q-laminations. In this paper we introduce an alternative
definition of an invariant lamination, which involves only conditions on the
leaves (and avoids gap invariance). The new class of laminations is slightly
smaller than that defined by Thurston and is closed. We use this notion to
elucidate the connection between invariant laminations and invariant
equivalence relations on $S^1$.
