matrix valued analytic functions, Functions whose values are linear operators (operator- and matrix-valued functions, etc., including analytic and meromorphic ones), Linear operators on spaces with an indefinite metric, Spaces with indefinite inner product (Kreĭn spaces, Pontryagin spaces, etc.), Pontryagin space, triplet spaces, Spaces of bounded analytic functions of one complex variable, symmetric relations, Hilbert spaces with reproducing kernels (= (proper) functional Hilbert spaces, including de Branges-Rovnyak and other structured spaces), Hilbert spaces of continuous, differentiable or analytic functions, spaces of vector-valued analytic functions, defect index