Terminations as well as their durations are defined in column 1 of the calendar ( variable Vcal_1). Each position in the calendar is associated to a date and they are represented by T followed by as many Ps. The pregnancy duration for the terminations are therefore defined by one month for the T plus as many months as Ps preceded. Variable V017 define the Century Month Code (CMC) of the start of the calendar and variable V018 define the row of the month of interview.