Arbitrary time (arb.time) - Dynamic NPU Manual

Arbitrary time (arb.time)



Definition in words

Arbitrary time of component B in system 1 compared with arbitrary time of component B in a reference system.

Note 1: Component B can be a reaction or proces

Note 2: The reference system is defined by the laboratory

Result type

Ordinal scale
  • Value set is ranked accoding to magnitude
  • The value set and the limit of the value set are defined by the laboratory
  • The value set can be either numerical values or words.

Example 1

Value set={none<some<high<very high}

Example 2

Value set={low<normal<high}

Example 3

Value set={0<1<2}

Example 4

Value set={negative<positive}

Example 5

Value set={+<++<+++}

  • Algebraic operations are not allowed (Ref. 2, 1.26)
  • Possible comparison of values (a<b, a=b or a>b)



Special rule(s) in the NPU syntax

“Procedure” is stated in the specification to the kind-of-property in the NPU definition

“Procedure” indicates that the measurement procedure must be stated somewhere else than the NPU code and there may be difficulties in comparing values for the same NPU code


Ferard G, Dybkaer R, Fuentes-Arderiu X. Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences : Recommendations 2016. 1 ed: Royal Society of Chemistry; 2016. 182 p. doi:10.1039/9781782622451

Laboratory field


Allergology Generic abbreviated form NPU14107 P—Coagulum lysis; arb.time(proc.) = ?
Full form with a result NPU14107 Plasma—Coagulum lysis; arbitrary time(procedure) = 2
Abbreviated form with a result NPU14107 P—Coagulum lysis; arb.time(proc.) = 2
Written expression The arbitrary time of Coagulum lysis in Mr. Smith’s plasma is [2] compared with the arbitrary time of Coagulum lysis in a reference system.

The reference system is defined by the laboratory.

“2” is a value according to a value set defined by the laboratory.

Reference NPU database, and
  • Kind-of-property

    • Nominal kind-of-property

    • Kind-of-quantity

      • Ordinal kind-of-quantity

        • Arbitrary time


  • Dybkaer R. Concept system on ‘quantity’: formation and terminology. Accredit Qual Assur. 2013;18(3):253-60.
  • Dybkaer R. ISO terminological analysis of the VIM3 concepts ‘quantity’ and ‘kind-of-quantity’. Metrologia. 2010;47(3):127-34.
Date Term Note
1996-01-01 Arbitrary time Term established