occbin_write_regime: periods option
the scope and use of the option is not to select for which periods to save the occasionally binding regimes, but to provide a more informative label to the periods, i.e. dates or real numbers representing years and quarters.
this is in fact the behaviour of the function which prints any array T that is user provided.
So, I would suggest to allow for
periods option to have not only integers, but also real, if not also dates arrays.