Metre Convention in the context of "Metrology"

In 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants, rather than human artefacts such as the standard kilogram. Effective 20 May 2019, the 144th anniversary of the Metre Convention, the kilogram, ampere, kelvin, and mole are defined by setting exact numerical values, when expressed in SI units, for the Planck constant (h), the elementary electric charge (e), the Boltzmann constant (k_B), and the Avogadro constant (N_A), respectively. The second, metre, and candela had previously been redefined using physical constants. The four new definitions aimed to improve the SI without changing the value of any units, ensuring continuity with existing measurements. In November 2018, the 26th General Conference on Weights and Measures (CGPM) unanimously approved these changes, which the International Committee for Weights and Measures (CIPM) had proposed earlier that year after determining that previously agreed conditions for the change had been met. These conditions were satisfied by a series of experiments that measured the constants to high accuracy relative to the old SI definitions, and were the culmination of decades of research.

The previous major change of the metric system occurred in 1960 when the International System of Units (SI) was formally published. At this time the metre was redefined: the definition was changed from the prototype of the metre to a certain number of wavelengths of a spectral line of a krypton-86 radiation, making it derivable from universal natural phenomena. The kilogram remained defined by a physical prototype, leaving it the only artefact upon which the SI unit definitions depended. At this time the SI, as a coherent system, was constructed around seven base units, powers of which were used to construct all other units. With the 2019 redefinition, the SI is constructed around seven defining constants, allowing all units to be constructed directly from these constants. The designation of base units is retained but is no longer essential to define the SI units.

The General Conference on Weights and Measures (abbreviated CGPM from the French: Conférence générale des poids et mesures) is the supreme authority of the International Bureau of Weights and Measures (BIPM), the intergovernmental organization established in 1875 under the terms of the Metre Convention through which member states act together on matters related to measurement science and measurement standards. The CGPM is made up of delegates of the governments of the member states and observers from the Associates of the CGPM. It elects the International Committee for Weights and Measures (abbreviated CIPM from the Comité international des poids et mesures) as the supervisory board of the BIPM to direct and supervise it.

Initially the work of the BIPM concerned the kilogram and the metre, but in 1921 the scope of the Metre Convention was extended to accommodate all physical measurements and hence all aspects of the metric system. In 1960 the 11th CGPM approved the title International System of Units, usually known as "SI".

"Chinese Taipei" is the term used in various international organizations and tournaments for groups or delegations representing the Republic of China (ROC), a country commonly known as Taiwan.

Due to the one China principle stipulated by the People's Republic of China (PRC, China), Taiwan, being a non-UN member after its expulsion in 1971 with ongoing dispute of its sovereignty, was prohibited from using or displaying any of its national symbols that would represent the statehood of Taiwan, such as its national name, anthem and flag, at international events. The term "Chinese Taipei" was first proposed in 1979 and was eventually approved in the Nagoya Resolution, whereby both the ROC/Taiwan and the PRC/China obtained their right of participation and would remain as separate delegations in any activities of the International Olympic Committee (IOC) and its associated organizations. This term came into official use in 1981 following a name change of the Republic of China Olympic Committee (ROCOC) to the Chinese Taipei Olympic Committee. This arrangement later became a model for the ROC/Taiwan to continue participating in various international organizations and diplomatic affairs other than the Olympic Games, including the World Trade Organization, the World Health Organization, the Metre Convention, APEC, and international pageants.