--------
In message 
<canx10hdf4y9klmplkgvlghrr_-8yunw0xsijknpgu_w6_7+...@mail.gmail.com>, "Dr. 
David Kirkby" writes:

> I am trying to work out what the BIPM definition of verification means
> 
> https://jcgm.bipm.org/vim/en/2.44.html
> 
> “ provision of objective evidence that a given item fulfils specified
> requirements”
> 
> [...]
> 
> The one sentence definition in VIM leaves me wondering what the intension
> of the entry is.

To rule out "because I say so" claims.

In the BIPM-adjucnt sphere, there is no such thing as "a measurement", there
are only "a measurement with uncertainty".

The objective evidence can either be that you have implemented the
definition of unit in question, (Cesium, Hall-effect etc.) in which
case the uncertainty is the uncertainty of your implementation.

Alternatively, you can establish a chain of measurements back to
such an implementation, in which case your uncertainty is the "proper
combination" of the uncertainties of each step in the chain, where
"proper combination" takes due account of the fact that time
elapses between each measurement in the chain.

In other word: Calibration Certificates.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
[email protected]         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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