Finite rank Butler groups and torsion-free modules over a discrete valuation ring

Fully faithful functors from isomorphism at $p$ categories of finite rank Butler groups to torsion-free modules of finite rank over the integers localized at a prime $p$ are constructed via categories of representations of antichains over discrete valuation rings. Descriptions and properties of modules in the images of these functors are given, including a characterization of finite representation type and a complete list of indecomposables in that case.