era_year objects describe the unit used for a year as its length in days.
This value is used in an era definition (
era()) to enable conversions
between eras that use different units (with
era_year(label = character(), days = 365.2425)
Character. Name of the year unit.
Numeric. Average length of the year in solar days. Defaults to a Gregorian year (365.2425 days).
S3 vector of class
era_year("Julian", 365.25)#> <era_year> #>  Julian years (365.25 days)