About Units and Z39.50

In the Z39.50 ASN.1 definitions, units of measure are expressed using the ASN.1 definition (from the APDU definitions) Unit and IntUnit:

• Unit is used to express a unit, without a value (for example to request that a particular value be sent according to a particular unit), for example "kilometers".
• IntUnit is used to express a value together with a unit, for example "ten kilometers".

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Unit is defined as:

  Unit ::= SEQUENCE{
     unitSystem      [1] InternationalString OPTIONAL,
     unitType        [2] StringOrNumeric OPTIONAL, 
     unit            [3] StringOrNumeric OPTIONAL, 
     scaleFactor     [4] IMPLICIT INTEGER OPTIONAL}

Unit system

provides the context for the unit type and unit. Systems in common use in the scientific and technical communities include SI, MKS, CGS, FPS, ENG, and STN. In addition to existing standard unit systems, the unit system 'z3950' will be used to register those unit types/units needed by implementors and not defined by other known systems. Values of unit type and unit under the system 'z3950'will be maintained by the Z39.50 Maintenance Agency.

Unit type

is, for example, 'Mass'.

Unit

is, for example, 'Kilograms' (when unit type is 'Mass').

Scale Factor

is an integer scale factor, base 10. For example, 9 would mean that the actual value is the given value times 10 to the -9 power.

  IntUnit ::= SEQUENCE{
    value      [1] IMPLICIT INTEGER,
    unitUsed   [2] IMPLICIT Unit}