The Application-Layer Traffic Optimization (ALTO) Service has defined network and cost maps to provide basic network information, where the cost maps allow only scalar (numerical or ordinal) cost mode values. This document introduces a new cost mode called path-vector to allow ALTO clients to support use cases such as capacity regions for applications. This document starts with a non-normative example called multi-flow scheduling (or capacity region) to illustrate that ALTO cost maps without path vectors cannot provide sufficient information. This document then defines path-vector as a new cost mode.