Passed on 8 Su'yet, LY 904, the surname law was a proposition which was voted into effect by the general public during the first ever world elections. It stated that everyone on The Land must choose a surname. (Because of their association with the establishment of the Second Order, it is not uncommon for people to refer to surnames as "Order names.") However, when the United Villages of the Chaos (the Land's second country) was established in 913, it was decided that this was one of the laws that would be recognized there, as well. (In fact, some of those who helped found the UVC, who had never taken surnames, now finally chose surnames for themselves.) The law was also adopted by Sorret and West Ocean in 913.
There were many proponents of this proposition, among both The Order and people running for political office. One of the most vocal of these proponents was Xander Illustri, who became a member of the council of Triscot. (Some people who knew Xander prior to the Coming of the Order have said that his clan actually used the surname "Illustri" before there were surnames on the Land... with the exception of the Elves, of course.) It must be noted that, though this wasn't known until 903, elves had been using surnames among themselves, in Woodstockade, since their third generation, at least a century ago. After their reintegration into human society, there was a great fascination about their culture (most people had no idea their race even existed), and this fascination was a large part of what inspired interest in the idea of Landian society in general adopting surnames. Of course, it also simply seemed like a logical idea, considering how much the population was increasing, and how much contact there now was between villages. There are of course many first names which are common, which was leading to more and more confusion. In the past, persons of prominence had often tacked the name of their village onto their names, though even that was an imperfect solution, considering there could be any number of people with the same first name within the same village. And so, the surname law was passed with the largest majority in history, the vote being very nearly unanimous. These names were officially recorded in 905, during the First Census.
Naturally, most people within a given clan chose to adopt the same surname, though individuals were free to choose their own name, for whatever reason. A clan might vote amongst themselves on what name to choose, or the head of a clan might choose his or her name, while their relatives simply went along with it. Usually these names would have to do with the business that the clan or head of clan was in, though there were also plenty of people who chose surnames for other reasons, possibly obvious and possibly obscure. It should also be noted that some people, such as Protestants or Streetrats, have chosen to adopt the same surname in spite of not being related to each other. (Of course, there are surely many members of such groups who don't go by such surnames.) Early after the passing of the law, the question arose of what should be done about surnames when two people married each other. Should they each keep their own name, should they hyphenate, should one choose to go by the other's name, etc.? The law does not account for this, so it is left up to the individuals involved, and different couples choose different courses. It is most common for them to decide which one's clan is more prominent, and the other will then choose to change their name accordingly. However, this is not always done; it's perfectly possible for the couple to choose to both go by the name of the less prominent clan. And of course, it's also common for two clans to be of equal prominence (or no particular prominence at all). Whatever the decision, if a person chooses to change his or her surname after marrying, they could simply do so unofficially, or they could file a request with the courts to have their name legally amended within the census records. Otherwise, they could simply wait for the next census, in 915, to make the change official.
There was no requirement that anyone explain their chosen names to the census-takers or anyone else, though in the years following the law's enactment, it has become popular among many people to explain their names to anyone they meet, as a way of getting to know each other. Some people have, in more recent years, even begun choosing middle names for themselves, for various reasons. This is by no means required, and such names won't be considered official until they are recorded, presumably, in the second census (unless, as with marriages, they petition the courts).