Unified Code for Units of Measure
The Unified Code for Units of Measure (UCUM) is a rule-based coding system for units of measure .
overview
The purpose of this standard is the electronic data exchange of physical quantities . UCUM is based closely on international standards ( ISO 2955–1983, ANSI X3.50-1986), which in turn are based on the SI system of units . The coding system enables compound expressions to be formulated for any units derived from the basic units. UCUM should combine uniqueness and arithmetic traceability to SI units with practical relevance, readability and applicability.
The OID for the UCUM coding system is 2.16.840.1.113883.6.8. The so-called system includes by definition all UCUM expressions that can be constructed according to the coding rules. The formal definition, code tables and example implementations can be found on the UCUM pages of the Regenstrief Institute .
In contrast to tabulated coding systems ( SNOMED CT , LOINC ), valid UCUM codes are composed of a relatively small number of "atomic" symbols and operators that are combined according to simple syntax rules.
The components of the definition of UCUM are:
- Basic units: A fixed list of basic quantities for length , mass , time , temperature , electrical charge , light intensity and angle .
- Prefixes: A fixed list of prefixes that can be used as symbols for multipliers (see prefixes for units of measurement , binary prefixes ).
- Derived units (atomic unit symbols): A fixed list of "atomic symbols", in which further units are listed together with conversion factors and formulas for tracing back to base units. Each unit in this list has a metric / non-metric attribute, which determines whether this unit can be combined with a prefix or not.
- Simple rules for combining symbols, along with some operators for multiplication , division , exponentiation and grouping brackets.
With these rules, an infinitely large number of valid units can be derived (a table-based approach, on the other hand, must necessarily be incomplete, see list of physical quantities ). The syntax rules together with the conversion factors contained in the definition tables enable the automatic and unambiguous conversion of physical quantities with the same dimension , which are specified in different units .
For the transmission of measured variables , for example as a result of an examination or clinical observation, the unit of measurement must be specified in HL7 Version 3 as a UCUM code. In addition to the standardized coding of units with UCUM, LOINC is a standard for the identification of measurement and examination methods .
Some organizations and standards that use UCUM codes recommend or prescribe:
- HL7
- DICOM
- Open Geospatial Consortium
- FDA - Center for Drug Evaluation and Research
- Centers for Disease Control and Prevention
- California Healthcare Foundation
Alternative approaches with comparable objectives can be found in the definition of a metric interchange format and in the document POSC RP66 V2 of the Petrotechnical Open Standards Consortium . However, both definitions do not adequately cover the conventional units used in medicine and biochemistry today.
See also
literature
- Gunther Schadow, Clement J. McDonald, Jeffrey G. Suico, Ulrich Föhring, Thomas Tolxdorff: Units of Measure in Clinical Information Systems. In: Journal of the American Medical Informatics Association. Vol. 6, No. 2, 1999, ISSN 1067-5027 , pp. 151-162, doi : 10.1136 / jamia.1999.0060151 .
Web links
- http://unitsofmeasure.org/ UCUM homepage and definition
- http://eclipse.org/uomo/ UCUM-Implementation UOMo at Eclipse.org (engl.)
Individual evidence
- ↑ regenstrief.org
- ↑ OpenGIS® Web Map Service Implementation Specification
- ↑ Data Standards Manual
- ↑ ELINCS specification ( Memento of the original from September 25, 2006 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ www-swiss.ai.mit.edu
- ↑ posc.org
