  This paper discusses some aspects of the Vasiliev system, beginning with a
review of a recent proposal for an alternative perturbative scheme: solutions
are built by means of a convenient choice of homotopy-contraction operator and
subjected to asymptotically anti-de Sitter boundary conditions by
perturbatively adjusting a gauge function and integration constants. At linear
level the latter are fibre elements that encode, via unfolded equations,
propagating massless fields of any spin. Therefore, linearized solution spaces,
distinguished by their spacetime properties (regularity and boundary
conditions), have parallels in the fibre. The traditional separation of
different branches of linearized solutions via their spacetime features is
reviewed, and their dual fibre characterization, as well as the arrangement of
the corresponding fibre elements into AdS irreps, is illustrated. This
construction is first reviewed for regular and singular solutions in compact
basis, thereby capturing massless particles and static higher-spin black holes,
and then extended to solutions in conformal basis, capturing bulk-to-boundary
propagators and certain singular solutions with vanishing scaling dimension,
related to boundary Green's functions. The non-unitary transformation between
the two bases is recalled at the level of their fibre representatives.
