On: Rulers of the Ancient World: period correct measur...

[Terr_]

> (Units of measures applicable to spies are left as an exercise to the reader.)

Well, if they were spying while employed as a tinker, a tailor, or a sailor...

Wouldn't it simply be whatever was readily available to someone in their cover identity?

[dredmorbius → Terr_]

Well, that would leave the issue of conversion factors, from cover to spy units ;-)