The month to be added to the year. Months 1 to 9
should be given as character strings, i.e. "01", "02", etc,
and not 1 or 2o, etc.
day
The day to be added to the year. Days should be given
as character strings, i.e., "01" or "02", etc, and not 1 or 2, etc.
Value
A vector of dates where the input integer forms the year
component. The day and month components added will by default
be the 15th of June, so that tick marks will appear in the
middle of the series on plots. For input, only years 0:9999 are
accepted.