Abbreviation
In Swedish, the colon is used in contractions, such as S:t for Sankt (Swedish for "Saint"), e.g. in the Stockholm metro station S:t Eriksplan. This can even occur in people's names, for example Antonia Ax:son Johnson (Ax:son for Axelson). The colon was also used to mark abbreviations in early modern English.
Read more about this topic: Colon (punctuation)