To describe a model 𝒫\mathcal{P} we use a parametrization, that is, a map θ→Pθ\theta \to P_{\theta} from a space of labels, the parameter space Θ\Theta, to 𝒫\mathcal{P}; or equivalently write 𝒫={Pθ:θ∈Θ}\mathcal{P} = \{P_{\theta} : \theta \in \Theta\}.