By default (though based on configuration) pub dates with "unknown" markers are normalized to the start of the unknown range for date1 and to the end for date2. So, a date1 of "199?" becomes "1990", and a date2 of the same becomes "1999".
By default (though based on configuration) pub dates with "unknown" markers are normalized to the start of the unknown range for date1 and to the end for date2. So, a date1 of "199?" becomes "1990", and a date2 of the same becomes "1999".