  We develop a functorial theory of spinor and oscillator representations
parallel to the theory of Schur functors for general linear groups. This
continues our work on developing orthogonal and symplectic analogues of Schur
functors. As such, there are a few main points in common. We define a category
of representations of what might be thought of as the infinite rank pin and
metaplectic groups, and give three models of this category in terms of:
multilinear algebra, diagram categories, and twisted Lie algebras. We also
define specialization functors to the finite rank groups and calculate the
derived functors.
