Type Alias: Base

Base = "year" | "years" | "y" | "month" | "months" | "M" | "week" | "weeks" | "w" | "day" | "days" | "d" | "hour" | "hours" | "h" | "minute" | "minutes" | "m" | "second" | "seconds" | "s" | "millisecond" | "milliseconds" | "ms"

The units of every operation: year, month, week, day, hour, minute, second, millisecond.