Dirac structures are used as the underlying structure to mathematically formalize
port-Hamiltonian systems. This note approaches the Dirac structures for
infinite-dimensional systems using the theory of linear relations on Hilbert spaces.
First, a kernel representation for a Dirac structure is proposed. The one-to-one
correspondence between Dirac structures and unitary operators is revisited. Further, the
proposed kernel representation and a scattering representation are constructively related.
Several illustrative examples are also presented in the paper.