Months of use of the current contraceptive method are calculated from the calendar for model "A" questionnaires, or are taken directly from the questionnaire for mode "B" questionnaires, and from the date of sterilization for women who are sterilized or whose partners are sterilized. For model "B" questionnaires, if the months of use are missing, unknown or inconsistent, then this variable is set likewise.
For Model "B" questionnaires, if the number of months of use exceeds 8 years, it is coded as 96. For Model "A" questionnaires, the month of interview is ignored in calculating the duration of current use in the calendar. For Model "A" questionnaires, if the woman is using the method throughout the calendar, the duration is coded as 95.