  Special Relativity is a cornerstone of modern physical theory. While a
standard coordinate model is well-known and widely taught today, several
alternative systems of axioms exist. This paper reports on the formalisation of
one such system which is closer in spirit to Hilbert's axiomatic approach to
Euclidean geometry than to the vector space approach employed by Minkowski. We
present a mechanisation in Isabelle/HOL of the system of axioms as well as
theorems relating to temporal order. Proofs and excerpts of Isabelle/Isar
scripts are discussed, particularly where the formal work required additional
steps, alternative approaches, or corrections to Schutz' prose.
