In message , at 11:41:56 on Mon, 6 Feb 2017,
tim... remarked:

Post-your=Brexit there's nothing to ensure that while the customs
people will let the stuff in, without a tariff, that the customer
will automatically discover it meets the standards.

That part is clearly within the SM

Hurrah!

but that is their problem

it isn't a reason why we should be part of, and achieve benefits
from, the CU

Are you now agreeing that the third of the following you listed
earlier is SM not CU:

No

because you are confusing

proof that you have met the SM rules

with having to account for the duty on the components/completed article

No I'm not. The distinction is clear.

AIUI the former is never done at borders and therefore does not impact
on the day to day costs of shipping goods.

Maybe not at internal borders, but if we take the apocryphal example of
straight bananas, they have to be checked when first imported into the
CU, but if that specification was in fact in force[1] then after we
leave the SM the UK could import mis-shapen bananas and then what's to
stop us shipping them to the Continent under CU?

[1] Other parts of the Directive still are, such as freedom from pests
and pesticides.

Of course it impacts on the initial design costs and possibly requires
certification (though mostly products are self certified on pain of
fines for getting it wrong).

Not all products with specifications are manufactured goods (see above).

But the people who are making that (I accept, perfectly valid) point
are attributing it to our leaving the SM, when the reality is that they
will come from us leaving the CU.

You are making the assumption that everything we export to the
rest-of-EU in future will continue to meet the standards, and thus not
require inspection a the border. But having left the SM, the specs will
drift apart. One of the most significant being discussed on other lists
I subscribe to is the much stricter Data Protection rules due to come in
between now and Brexit, while the UK government is busy passing laws
which water down the existing rules.

One of the things we export (under that SM umbrella) is data hosting and
processing facilities.
--
Roland Perry