The question deals with correlation between the US and European
industrial code classifications.

If you can answer it, you won't need the following clarification, but
for the sake of good order:

US (and Mexican and Canadian) NAICS codes classify industries through
increasing levels of refinement. Each sector of the economy has been
defined so that organizations which do similar things in similar ways
are grouped together. NAICS can work down to six digits ? the first
five are standardized across the three countries, but the individual
countries may specify the sixth digit as they choose.

The NAPCS is an emerging product classification system based on NAICS,
and will be similarly applied by the U S, Canada and Mexico. To
support international comparison of data they have agreed to try to
make NAPCS correlate with the United Nations Central Product
Classification code (CPC) as far as possible.

The European Community has had a different system of industrial
activity classification called the CPA, which has links to the United
Nations CPC code down to the fifth and sixth digit. This is being
replaced by PRODCOM, which extends the CPA code structure from six to
eight digits.

So: NAPCS will tie in with CPC which is linked to CPA and therefore to PRODCOM

I want a concordance between PRODCOM and NAPCS down to six or if
possible eight digits, not for all products, but for as many as are
possible. I know there are some highly specialized schemes that
provide a common starting point from which to begin international
comparisons, for example in the chemical industry.

Are there any others, or is there a commercial source for this data?

Hi greg33,

At the following four links, you will find more links to .pdf  NAPCS
completed product lists.  The lists include the NAICS Classification
and the CPC Code.  After searching the internet for quite awhile, I
believe that these documents are the closest you are going to come to
what you are looking for at the present time. As my sixth link states,
"Do conversion tables exist between the national and the international
classifications (if applicable)?
No, the system is still in development. However, we are including CPC
links for each of the products in our product lists."

Phase I sectors completed:

NAICS 51-Information Sector
Product List Development Under Phase I of NAPCS
http://www.census.gov/eos/www/napcs/prodlist51.htm

NAICS 52-Finance and Insurance Sector
Provisional Product Lists Developed Under Phase I.1 of NAPCS
http://www.census.gov/eos/www/napcs/prodlist52.htm

NAICS 54-Professional, Scientific, and Technical Services Sector
Product List Development Under Phase I of NAPCS
http://www.census.gov/eos/www/napcs/prodlist54.htm

NAICS 56-Administrative and Support and
Waste Management and Remediation Services
Provisional Product Lists Developed Under Phase I.1 of NAPCS
http://www.census.gov/eos/www/napcs/prodlist56.htm

NAPCS Overview
Phase II sectors in progress:
Transportation and Warehousing (Sector 48-49)
Education Services (Sector 61)
Health and Social Assistance (Sector 62)
Arts, Entertainment and Recreation; Accommodation and Food Services (Sectors 71-72)
http://www.census.gov/eos/www/napcs/napcs.htm

National Classifications NAPCS
Do conversion tables exist between the national and the international
classifications (if applicable)?
No, the system is still in development. However, we are including CPC
links for each of the products in our product lists."
The NAPCS Website (http://www.census.gov/napcs) contains detailed
background information on NAPCS and on 26 of the product lists
completed to date.
http://unstats.un.org/unsd/cr/ctryreg/ctrydetail.asp?id=264

Additional Links of Interest:

Concordances to other industry classifications
NAICS Canada 2002
http://www.statcan.ca/english/concepts/industry.htm

"A new  North American Product Classification System (NAPCS) is
presently under development, with initial focus on products of service
industries. (NAPCS will focus on manufacturing products at a later
date; for existing census codes, see the  Numerical List.)"
http://www.census.gov/prod/ec97/97numlist/97numlist.html

I hope you find the NAPCS Product Lists satisfactory. If you have any
questions, please post a clarification request and wait for me to
respond before closing/rating my answer.

Thank you,
hummer

Some Google Search Terms Used (I used many combinations): NAPCS codes
classifications PRODCOM digits "North American Product Classification
System" product list development