  The MT2 or "s-transverse mass" statistic was developed to associate a parent
mass scale to a missing transverse energy signature, given that escaping
particles are generally expected in pairs, while collider experiments are
sensitive to just a single transverse momentum vector sum. This document
focuses on the generalized extension of that statistic to asymmetric one- and
two-step decay chains, with arbitrary child particle masses and upstream
missing transverse momentum. It provides a unified theoretical formulation,
complete solution classification, taxonomy of critical points, and technical
algorithmic prescription for treatment of the MT2 event scale. An
implementation of the described algorithm is available for download, and is
also a deployable component of the author's selection cut software package
AEACuS (Algorithmic Event Arbiter and Cut Selector). Appendices address
combinatoric event assembly, algorithm validation, and a complete pseudocode.
