  Chemical gradients can be used by a particle to determine its position. This
\textit{positional information} is of crucial importance, for example in
developmental biology in the formation of patterns in an embryo. The central
goal of this paper is to study the fundamental physical limits on how much
positional information can be stored inside a system. To achieve this, we study
positional information for general boundary-driven systems, and derive, in the
near-equilibrium regime, a universal expression involving only the chemical
potential and density gradients of the system. We also conjecture that this
expression serves as an upper bound on the positional information of boundary
driven systems beyond linear response. To support this claim, we test it on a
broad range of solvable boundary-driven systems.
