Scandinavia
In Denmark and Norway, the term middle name refers to names that are originally surnames, but not part of the last name of the name bearer. A middle name could be e.g. one's mother's maiden name or the last name of another recent ancestor (for instance a grandparent). One can have several middle names, but it is unusual to have more than one or two. In law, middle names have a separate status. In practice, their status is similar to that of additional given names, and middle names are often omitted in everyday use, just like a person with 3 or 4 given names would only use one of them in most situations. The historical purpose of middle names is to honour some related family or person. Until the 19th century, it was not unusual to have the last name of a godparent as one's middle name, even when the godparent was no blood relative. This practice, and the use of middle names in general, however, was mostly limited to the bourgeois class and the nobility, and was seldom seen among common people. In the 20th century, the use of middle names, especially one's mother's maiden name, was more widely adopted, although it is by no means mandatory. There are few set rules for how names are constructed today; people are required to have one given name and one family name, but can have as many additional given names and middle names as they like.
In the example Carl Viggo Manthey Lange, the names Carl and Viggo are given names, while Manthey is a middle name and Lange is the family name. Manthey is his mother's maiden name. Unless his full name is used, he is correctly referred to as Mr. Lange, not as Mr. Manthey Lange. Carl Viggo Manthey Lange has a name typical of the Norwegian bourgeois class, with both his family name and his middle name being of foreign origin and being recognised surnames. Most Norwegians and Danes of the working class and peasant class used patronymics until the 19th century, when permanent family names became mandatory, first in Denmark in the early 19th century and then in Norway around 1900. A middle name is usually a recognised surname and not a patronymic. One reason middle names have become popular in the 20th century, particularly in Denmark, is that most Danish surnames originated as patronymics and are shared by a large number of people. The use of middle names in modern times serves to differentiate them from other people. For example, Danish politician Lars Løkke Rasmussen has some of the most common given and last names in Denmark (Lars and Rasmussen); his mother's maiden name is the slightly more unusual name Løkke, derived from a small agricultural property, so he uses it as a middle name, which differentiates him from other people named Lars Rasmussen.
In Sweden, the position is much the same as in Denmark. Middle names were inaugurated in the previous Name Act of 1963, then called "tilläggsnamn" (additional name), and are called "mellannamn" (middle name) as of the present Name Act of 1983. However, it had previously been more common to join e.g. the last names of a child's both parents, or for a married woman to join her maiden name and the husband's last name, as a double name with a hyphen, and commonly, large portions of the Swedes have not adapted to the official system to this day, i.e. for almost 50 years. People often use a hyphen between their middle name and last name themselves, and/or are spelled that way by other people. Not even mass media know things correctly, but contribute to misinterpretations.
Furthermore, when the term middle name was introduced in Swedish ("mellannamn") the word was assumed by many to mean the additional given names (apart from the "name of address" (tilltalsnamn)), so since 1983 the word is being used more and more in this, officially, erratic meaning.
Occasionally, Scandinavians choose to use their middle name as their surname in everyday life. So Per Gottfrid Svartholm Warg has Per and Gottfrid as his given names, where Gottfrid, not Per, is his name of address, Svartholm as his middle name and Warg as his last name, but in practice he uses Svartholm as a surname. This usage, however, is unofficial. Historically, a middle name could become part of a double-barreled surname (family name) and hence cease to be a middle name, especially if used for several generations. There are many family names of this kind, which contributes to the confusion about middle names that shall not be hyphenated. Some of these double-barreled surnames are combined with a hyphen, while others are not, so a double surname without a hyphen can sometimes be indistinguishable from a middle name followed by a family name.
In Scandinavia, there is no limit on how many given names one can have. Given names have never been referred to as middle names, apart from many in Sweden believing so, as mentioned above. The use of more than two given names is generally associated with the upper class. The first given name is not necessarily the name of address. For the sake of completeness, Swedish forms often ask people to fill in all their given names and to indicate which one is their "name of address" (tilltalsnamn).
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