Arbitrary shear stress (arb.shear stress) - Dynamic NPU Manual

Arbitrary shear stress (arb.shear stress)


Arb.shear stress

Definition in words

Arbitrary shear stress of component B in system 1

Note: Shear stress is “Force acting tangentially to a surface divided by the area of the surface” IUPAC Gold Book

Definition by equation

Note: kprocedure is a constant defined by the measurement procedure (there is an approximately proportionality to a kind-of-quantity from the International System of Quantities).

Ratio scale
  • Value sets are positive numerical values
  • Numerical values from 0-∞
  • Algebraic operations are allowed
  • Possible comparison of values (a=nb; a≠nb)


International unit (IU) or procedure defined unit (p.d.u.) (non-SI units)

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.

If the unit is an International Unit (IU), an international certified reference material (e.g. WHO reference material) is specified in the specification to the kind-of-property.

If there exist no international certified reference material, the laboratory can specify the unit at the placeholder, procedure defined unit.


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


Thrombosis and Haemostasis

Generic abbreviated form

NPU54277 B—Coagulum shear strength(heparin indep.); arb.shear stress(surf. and tissue f.induc.coag.; proc.) = ? (p.d.u.)

  NPU54277 Blood—Coagulum shear strength(heparin independent); arbitrary shear stress(surface and tissue factor induced coagulation; procedure) = 25 arbitrary unit
Abbreviated form with a result NPU54277 B—Coagulum shear strength(heparin indep.); arb.shear stress(surf. and tissue f.induc.coag.; proc.) = 25 arbitrary unit
Written expression The arbitrary shear stress of heparin independent Coagulum shear strength is [25] arbitrary units. The measurement is performed according to a surface and tissue factor induced coagulation procedure defined by the laboratory.

“Arbitrary unit” was chosen by a local laboratory as a proprietary measurement unit.and notan  accepted international unit.


NPU database, and
    • Kind-of-property

      • Nominal kind-of-property

      • Kind-of-quantity

        • Unitary kind-of-quantity

          • Rational unitary kind-of-quantity

            • Arbitrary shear stress


  • 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
2013-05-15 Arbitrary shear stress Term established