Joseph B. Reid wrote:
>>The dispute is about whether all metric systems but SI
>>can be regarded as invalid today.
>>That appears to be the NIST position.
>
>That appears to be the NIST position,
Thanks for clarifying that we agree on this point at least.
>but it is too strong.
I understand that you disagree with the position.
>See para. "4.2 Other non-SI units" in the metric bible.
>It advises "their use is not encouraged". It points out
>that there are three centimetre-gram-second systems of
>units in the field of electricity and magnetism,
>viz. the CGS Electrostatic System, the CGS
>Electromagneic System and the CGS Gaussian System.
Yes. It does mention previous metric systems. This can be read as
consistent with currently valid parallel metric systems (as many people
here think). Or it can be read as consistent with historical context to
a singular metric system that invalidates all those that went before (as
I think and the NIST apparently thinks).
One of my big criticisms of the SI brochure is that it embeds SI
guidelines in historical story telling. This makes it very difficult for
the reader to extract current validity from previous validity that is
now invalid.
The BIPM should satisfy their enthusiasm for publishing a museum
guidebook by some other means. Published guidelines for my clients
should follow the universal convention in standards/regulations and only
contain current rules and rationale ('Do this...because...').
