Logo of the Physikalisch-Technische Bundesanstalt
Symbolbild Struktur

Department 9.4

Metrology for data

Topic: Metrology for data

Metrological data with their metadata form a common basis for an innovative and progressive digital transformation in metrology. The topic area pursues the development and harmonization of suitable universal data standards that can be read and interpreted automatically by machines and software in the future. This is crucial for areas such as Industry 4.0, the Internet of Things (IoT) or Smart Cities in which decisions will increasingly be made without human interaction based purely on data. For research, it provides an important contribution to the interoperability and reusability of data from different sources. All these areas benefit from a data quality infrastructure supported by standardization, accreditation and metrology.

D-SI metadata model

The Digital System of Units (D-SI) metadata model provides a modular system for users to represent fundamental values of physical quantities in a uniform and machine-readable digital form. The elements of the data model provide a universal language for the interexchange of real, complex, and vector metrology data. Three of the basic principles of the D-SI are: 

·         „Atom“

The minimum requirement is the specification of a numerical value together with the assigned unit of measure (preferably SI units).

·         Internationally accepted guidelines

The data model is based on universal metrological guidelines such as the International System of Units (SI), the International Vocabulary of Metrology (VIM) and the Guideline for the Expression of Uncertainty in Measurement (GUM).

·         Simplicity

The D-SI reduces the multitude of analog representation options for measured values and uncertainties to a minimum number of relevant digital variants. The decisive factor for the selection of variants in the D-SI is the associated accuracy achieved when exchanging the digital data.


Additional technical information, documentation and sample applications are provided in Opens external link in new windowPTB GitLab Repository.


The D-SI as a central building block for future machine-to-machine communication of metrological data.
(The D-SI is a result of the EU-funded EMPIR project 17IND02 SmartCom).