>>>> I would have expected that for this frequency the
>>>> "micro"-frequency should refer to the calendar week.
> Given the periodicity 52 perhaps the "minor" frequency would make
> even more sense, thinking about a year:week structure.
Yes, in case one works with weekly data, the "minor" frequency should
be the calendar week. Also, I am not sure what the value added of a
"micro" frequency would be in this case. So "year:week" would be
Just as a follow up: Python's Pandas library also keeps the structure
<year:month:day> for weekly data. Also <pandas.DatetimeIndex.freq>
involves a series with 52 unique discrete values exactly corresponding
to what gretl's seasonals() function returns (even though you get a list
of series here). So I guess things are fine as they are in gretl ;-)