SI DIGITAL FRAMEWORK

This service constitutes the authoritative digital reference for the International System of Units (SI). It provides Permanent Digital Identifiers (PIDs) for the named SI units, SI prefixes, and defining constants, and a parsing tool for the PID and semantic model for compound units.

• SI Reference Point
  • Units
    Lists the named SI units
  • Prefixes
    Lists the SI prefixes
  • Defining Constants
    Returns the defining constants of the SI
  • Decisions
    Returns the decisions of the CGPM and the CIPM bearing directly upon definitions of the units of the SI, prefixes defined for use as part of the SI, and conventions for the writing of unit symbols and numbers.

This service provides PIDs for the kinds of quantity included in the SI Brochure and the KCDB, including a parsing tool for the PID and semantic model for compound quantities, and shows the related Service Categories in the KCDB.

• Quantities
  Lists the kinds of quantity included in the KCDB.
• Quantity expressions
  A parsing tool to provide the PID and semantic model for compound quantities.
• Service Categories
  This service shows the related service categories (KCDB) by quantity.

The digital services from the Consultative Committee for Thermometry (CCT) provide internationally-agreed reference data for temperature scales and measurements. The reference data sets here are sourced from documents related to the Mise en pratique for the definition of the kelvin in the SI and support the realization of scale temperatures via the International Temperature Scale of 1990 (ITS-90) and Provisional Low Temperature Scale of 2000 (PLTS-2000), and the realization of thermodynamic temperature via primary radiometric measurements and acoustic gas thermometry.

• Consultative Committee for Thermometry (CCT)
  • ITS-90
    International Temperature Scale of 1990 (ITS-90)
  • PLTS-2000
    Provisional Low Temperature Scale of 2000
  • Primary radiometric temperature measurement
  • Acoustic gas thermometry