standard library package ISQ {
    doc
    /*
     * International system of quantities (ISQ), as defined in ISO/IEC 80000
     */

	private import ScalarValues::Real;
	private import Quantities::*;
	private import MeasurementReferences::*;

	public import ISQBase::*;                  // ISO/IEC 80000 base quantities and general concepts
    public import ISQSpaceTime::*;             // ISO 80000-3 "Space and Time"
    public import ISQMechanics::*;             // ISO 80000-4 "Mechanics"
    public import ISQThermodynamics::*;        // ISO 80000-5 "Thermodynamics"
    public import ISQElectromagnetism::*;      // IEC 80000-6 "Electromagnetism"
    public import ISQLight::*;                 // ISO 80000-7 "Light"
    public import ISQAcoustics::*;             // ISO 80000-8 "Acoustics"
    public import ISQChemistryMolecular::*;    // ISO 80000-9 "Physical chemistry and molecular physics"
    public import ISQAtomicNuclear::*;         // ISO 80000-10 "Atomic and nuclear physics"
    public import ISQCharacteristicNumbers::*; // ISO 80000-11 "Characteristic numbers"
    public import ISQCondensedMatter::*;       // ISO 80000-12 "Condensed matter physics"
    public import ISQInformation::*;           // IEC 80000-13 "Information science and technology"

    /* Additional quantity declarations */

    attribute def TemperatureDifferenceValue :> ScalarQuantityValue {
        doc
        /*
         * temperature difference
         * A separate temperature difference quantity and unit are needed in order to support °C, °F and centrigrade temperature differences
         */
        attribute :>> num: Real;
        attribute :>> mRef: TemperatureDifferenceUnit[1];
    }
    
    attribute temperatureDifference: TemperatureDifferenceValue [*] nonunique :> scalarQuantities;

    attribute def TemperatureDifferenceUnit :> SimpleUnit {    
        private attribute thermodynamicTemperaturePF: QuantityPowerFactor[1] { :>> quantity = isq.'Θ'; :>> exponent = 1; }
        attribute :>> quantityDimension { :>> quantityPowerFactors = thermodynamicTemperaturePF; }
    }
}