LUCIFER, V8, Anal, Christ: these are among the baby names rejected by New Zealand's department of internal affairs, who recently released a comprehensive list of those disallowed by registrars in the past ten years. Though no name is banned outright, says Ross McPherson, the deputy registrar-general, some applications were not even words. Disappointed parents included those wishing to christen their offspring with numbers (89), letters (J, I, T) and punctuation marks (*).

Few decisions are more personal than the naming of offspring. Yet laws regulating the choice of both first names and surnames are common around the world. Denmark expects new parents to choose from a register of acceptable names; Portugal lists banned and approved ones. In Iceland a committee of language specialists must rule on any unusual name. German registrars prohibit the use of most nouns and place-names, and also frown upon any that do not clearly imply a gender: bad luck, Kim. Experts at a German-language society run a helpline offering advice to puzzled parents (at a cost).

Governments argue that these rules prevent children being saddled with preposterous names (Sinbin) that may cause them problems in later life. They also aim to block names that might cause offence to others (Jesuswept). Even where registrars have no power of prohibition, worrisome choices can be referred to judges or to child-protection agencies. In 2009 a couple in New Jersey lost custody of a boy they had named Adolf Hitler.

Less noble concerns play a role, too. First names that imitate lofty titles remain the most frequently disallowed in New Zealand. Registrars often frustrate enterprising parents trying to name their infants Justice, King, Prince, Baron and Duke. Strict laws in Sweden once aimed to stop people creating family names that imitated those already in use, says Staffan Nyström at Uppsala University. Requests to change a last name must still pass through the patent office there. Patriarchy remains entrenched in countries like Italy that refuse to allow married women to pass their maiden names on to their children, even in a double-barrelled surname.

Over time, the rules have eased. France scrapped its saint-strewn list of acceptable names in 1993. Two years later Iceland stopped requiring immigrants to adopt local names. The new constraint is technological, not bureaucratic. Government databases may struggle with long names: New Zealand allows 100 characters for all first names; the state of Massachusetts has a limit of 40 for each. Chinese face a particular difficulty: their language has tens of thousands of characters, but a name that uses archaic or rare ones can mean computer problems. Japanese parents with a penchant for the arcane face similar difficulties. Most countries ban names spelled in foreign alphabets, and many restrict the use of foreign diacritical marks: that fuels a row between Lithuania and Poland. Carlton Larson at the University of California notes that his state's registrars, unusually, ban all such dots and squiggles. So in America's most Spanish-speaking state it is impossible to christen a boy José.