Sheng nu cites studies that show that women are now breaking the tradition of "mandatory marriage" to have fewer children or marry later on in life. Other typologically similar terms that are still used in the modern lexicon of other countries and cultures show the concept has existed in some cases as far back as the 16th century. The term spinster was used to describe unmarried or single women of a marriageable age. It wasn't until 2004 when the Civil Partnership Act replaced the word spinster with "single" in the relationship history section of marriage certificates in the UK. Subsequently, at the
White certificates White certificates In environmental policy, white certificates are documents certifying that a certain reduction of energy consumption has been attained. In most applications, the white certificates are tradable and combined with an obligation to achieve a certain target of energy savings. Under such a system, producers, suppliers or distributors of electricity, gas and oil are required to undertake energy efficiency measures for the final user that are consistent with a pre-defined percentage of their annual energy deliverance. If energy producers do not meet the mandated target for energy consumption they are required to pay a penalty. The white certificates are