ξ is the currency symbol for value time and it defaults to a decimal quantity of hours.
ξ40 is “forty hours” of value time—and you could think of it as the equivalent of an American 40-hour work week. “Minimum wage” in ξ is the equivalent amount of wall-clock time. Exclusive skilled labor is typically paid at a ξ-rate greater than wall-lock time. For example, a plumber fixing a sink in a half-hour may charge ξ3 for labor and some other amount for parts as yet undetermined. If you’re earning less ξ than wall-clock time, you’re losing money.
Shared skilled labor is typically paid by a divided amount. A teacher in a class room might work for 1.5-hours with 30 students. What should the teacher be paid? The “minimum” would be ξ0.05 per student, but a skilled and experienced teacher should be paid much more. Since the teacher is a shared resource, the individual rate per student could be ξ0.25 per class, but in the aggregate, the teacher is earning ξ7.5 per 1.5-hour class.