Quantities, Units, Dimensions and Types (QUDT) - Level 1

This property relates a unit of measure with a unit system that does not define the unit, but allows its use within the system. An allowed unit must be convertible to some dimensionally eqiuvalent unit that is defined by the system.

This property associates a system of quantities with an enumeration that enumerates the base dimensions of the system in canonical order.

This property relates a unit of measure to the system of units in which it is defined as a base unit for the system. The base units of a system are used to define the derived units of the system by expressing the derived units as products of the base units raised to a rational power.

This property relates a unit of measure to the unit system in which the unit is derived from the system's base units with a proportionality constant of one.

A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one.

A system of units is coherent with respect to a system of quantities and equations if the system of units is chosen in such a way that the equations between numerical values have exactly the same form (including the numerical factors) as the corresponding equations between the quantities. In such a coherent system, no numerical factor other than the number 1 ever occurs in the expressions for the derived units in terms of the base units.

The default element in an enumeration

This property relates a unit of measure with the unit system that defines the unit.

This property relates a unit of measure to the system of units in which it is defined as a derived unit. That is, the derived unit is defined as a product of the base units for the system raised to some rational power.

An element of an enumeration

This property relates a quantity kind to its generalization. A quantity kind, PARENT, is a generalization of the quantity kind CHILD only if

1. PARENT and CHILD have the same dimensions in every system of quantities;
2. Every unit that is a measure of quantities of kind CHILD is also a valid measure of quantities of kind PARENT.

a property to relate an observable thing with a quantity (qud:Quantity)

This property relates a quantity kind to its specialization(s). For example, linear velocity and angular velocity are both specializations of velocity.

This property relates a unit system with a unit of measure that is not defined by or part of the system, but is allowed for use within the system. An allowed unit must be convertible to some dimensionally eqiuvalent unit that is defined by the system.

This property relates a system of units to a base unit defined within the system. The base units of a system are used to define the derived units of the system by expressing the derived units as products of the base units raised to a rational power.

A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one.

This property relates a unit system with a unit of measure that is defined by the system.

This property relates a system of units to a unit of measure that is defined within the system in terms of the base units for the system. That is, the derived unit is defined as a product of the base units for the system raised to some rational power.

This property relates a system of units with a unit of measure that is either a) defined by the system, or b) accepted for use by the system and is convertible to a unit of equivalent dimension that is defined by the system. Systems of units may distinguish between base and derived units. Base units are the units which measure the base quantities for the corresponding system of quantities. The base units are used to define units for all other quantities as products of powers of the base units. Such units are called derived units for the system.

A reference to the unit of measure of a quantity (variable or constant) of interest.

This property relates a unit of measure with a system of units that either a) defines the unit or b) allows the unit to be used within the system.

A property to relate an observable thing with a quantity value (qud:QuantityValue)

The currency exponent indicates the number of decimal places between a major currency unit and its minor currency unit. For example, the US dollar is the major currency unit of the United States, and the US cent is the minor currency unit. Since one cent is 1/100 of a dollar, the US dollar has a currency exponent of 2. However, the Japanese Yen has no minor currency units, so the yen has a currency exponent of 0.

An abbreviation for a unit is a short (usually 5 characters or less) string that is used in place of the full name for the unit in contexts where space is limited, or where using the abbreviation will enhance readability.

A unit code is a numeric string that uniquely identifies a unit

A negative change limit between consecutive sample values for a parameter. The Negative Delta may be the encoded value or engineering units value depending on whether or not a Calibrator is defined.

A positive change limit between consecutive sample values for a parameter. The Positive Delta may be the encoded value or engineering units value depending on whether or not a Calibrator is defined.

The relative standard uncertainty of a measurement is the (absolute) standard uncertainty divided by the magnitude of the exact value.

The standard uncertainty of a quantity is the estimated standard deviation of the mean taken from a series of measurements.

The symbol for a unit is a glyph that is used to represent the unit in a compact form. For example, the symbol for the US Dollar is $. This contrasts with unit:abbreviation, which gives a short alphanumeric abbreviation for the unit. (I.e. USD for US Dollar).