JEDDAH: Feb. 14 this year was a curious day in Saudi Arabia, the day on which more than 3.5 million Saudis — about a tenth of the population — celebrated their birthday. When identification cards became mandatory in the Kingdom more than 60 years ago many of those who came forward to register had no idea of their precise date of birth. The older generation of Saudis marked their birthdays by the year of their birth, neglecting the day and month — only a very few knew their exact date of birth, either by a memento such as newspaper clipping or from official birth certificates. To resolve this headache, about 45 years ago the Ministerial Agency of Civil Affairs chose to register the first of Rajab, the seventh month in the Hijri calendar — 1/7 — as the date of birth for millions of Saudis, even though some of them did know which day they were born on in the Gregorian calendar. The Hijri is the Islamic calendar that is used for official dates.