Recuerdo que John, tenía en su sitio una pagina dedicada al
NTDB, pero que despues que renovar su sitio web se perdió...
Bueno gracias a la ayuda de archive.org podemos ver como era y beneficiarnos de su contenido
http://web.archive.org/web/20111228141451/http://www.johnspiers.com/NTDB.html
Copy/Paste de lo obtenido del sitio de John (Gracias archive.org):
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If importing, we must find the best place in the world
to have your product made; if exporting, we must find the best
customers in the world. My courses and book explain this, but
there is one step in the process that changes with technology,
so must be constantly updated. That step is referred to as the
"NTDB Research" step (NTDB = National Trade Data Bank),
and here is where I maintain a current set of instructions on
how to extract raw trade data from the NTDB. My book and courses
lay out how to analyze the data. You need first to get your Harmonized
Tariff Number which identifies your product, and then the raw
data to analyze.
All of this is free of charge.
Before you take my tutorial, you may want to download a .pdf of the
tutorial the USITC offers, and warm up with that, copy and paste this
url into your browser to download a .pdf.
http://dataweb.usitc.gov/DataWeb_Quick_Query_HowTo.pdf
1. All products imported into the United States are declared
to United States Customs Service, and Customs passes the declarations
on to US Census to tabulate the data by month and publish the
results. All products are declared by a number known as the Harmonized
Tariff Schedule number (HTS). You can look the number for your
product up yourself at this website:
http://www.usitc.gov/tariff_affairs/
It should look something like this:

Dead center of the page it says:
Tariff Affairs Products
Click on
" HTS by chapter"
You will be taken to a page that looks like this:

2. You may then scroll down through the categories and click
on your category, then download a .pdf file of the product category
you are considering.
Let's say I am looking for terra cotta siding, so I read through
the various chapter headings and click through to ceramics and
clay.
You already have had experience downloading .pdf files and
here you will have to do it again. Click on the appropriate link
and download the chapter to your computer to study. No doubt you
will have questions.
3. You may run into problems and questions, so there is an
inquiry form you may use at:
http://www.usitc.gov/tata/contact/index.asp

You may need to write a n email such as this...
Dear Sir,
I am researching import trade data on terra cotta siding and
need the right HTS number, but I am unsure which number exactly
covers my item. I think it is one of these:
6908 Glazed ceramic flags and paving, hearth or wall tiles;
glazed ceramic mosaic cubes and the like, whether or not
on a backing:
6908.10 Tiles, cubes and similar articles, whether or not
rectangular, the largest surface area of which is
capable of being enclosed in a square the side of
which is less than 7 cm:
6908.10.10 00 Having not over 3229 tiles per square meter, most
of which have faces bounded entirely by straight
lines .................................... m 2 ..... 12% Free
(CA,D,E,IL,J) 55%
7.9% (MX)
8.4% (JO)
Other:
6908.10.20 00 The largest surface area of which is less than
38.7 cm 2 .............................. m 2 ..... 12% Free (A*,CA,E,IL,
55%
J,MX)
8.4% (JO)
6908.10.50 00 Other ................................ m 2 .....
10.6% Free (CA,D,E,IL,J)
55%
7.5% (MX)
7.6% (JO)
6908.90.00 Other ...............................................
10.6% Free (CA,D,E,IL,J)
55%
7.5% (MX)
7.6% (JO)
10 Tiles, the largest surface area of which is capable
of being enclosed in a square the side of which is
30 cm or more ............................ m 2
50 Other ...................................
Thanks!
John Spiers
***
And then comes the reply...
***
. Dear Mr. Spiers,
You mentioned "terra cotta siding," which I assume
is in the form of large tiles. In order for these products to
fall in heading 6908, they must be glazed. If unglazed they would
fall in
heading 6907. If in 6908, they would likely not fall in subheading
6908.10,
as the tiles in that heading are pretty small, used more for a
mosaic
effect. Larger tiles would fall in subheading 6908.90.00.
You can see the full texts of these headings and subheadings
on our website
(http://www.usitc.gov), under "Publications", latest
edition of the
Harmonized Tariff Schedule.
If you need more clarification, let me know.
Dave Beck
4. Once you have worked with these fine people in ascertaining
your HTS number, then you go to another website, o extract the
raw trade data from the NTDB. You will be asked to create a niickname
and a password the first time you you it.
http://dataweb.usitc.gov/scripts/user_set.asp

Here you register as a user for free. Once you've done this,
click through to the data-generating engine, and set your search
parameters over the course of several pages:
U.S. Imports For Consumption
HTS Items
Current U.S. Trade (1996-2001)

Hit the Proceed button.
4. Set the report parameters:
a. Data Selection:
Shift-click to select data to report on...customs value/first
unit of quantity (both)
b. Select years to display
(shift select last five years)
c. Select all commodities or a pre-defined list:
i. hit Create a New Commodity List button
ii. select a list type - highlight HTS10 Imports hit Select
Commodity Level button.
iii. To create a new list enter a name like "near beer"
(whatever you ae importing) then click here Make a new list button.

iv. follow directions: highlight the chapter or category that
has your items:
(in this case #22 - beverages spirits and vinegar). Click Show
Items and page will refresh with chapter items in lower right
of page.

v. scroll through until your 10 digit HTS item comes up. Click
arrow left copy number button, page will refresh with number on
left. Hit "return to query design page" button.
vi. Highlight your item in "Select all commodities or
a pre-defined list:" in this case for me, HST10-IMP -- near
beer.
d. Select all countries or a pre-defined list:
"Select All Countries"
e. Leave the rest alone on the left "Data Selection"
side, and click the following buttons on the right " Data
Presentation" side:
Actual...Annual...HTS 10...Display Commodity Description...Display
Countries Separately
and leave other fields alone.
Now hit the Proceed to Next Step button at the bottom of the
page.
5. Highlight HTS10 and push the arrow right button, await screen
refresh; highlight HTS10 and push the arrow right button, await
screen refresh. Now Order of Key Fields In Report is HTS10 and
then country.

Now hit the Proceed to Next Step button at the bottom of the
page.
6. Now leave everything alone, except "Select the year
to sort on:"
Highlight 2001
Then hit the Run report button
You ought to have a full report, one you can use as raw data
to your analysis as laid out in the book. If not review your steps
carefully, and contact teh USITC experts above to help you resolve
the problems you are encountering.
This is NOT what you'll find in the libraries and what is sold
for $300 by the commerce dept... this data is more raw, but it
reminds me of what I use to use in the good old days of pen, paper,
calculator and printed reports.
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Fin del copy-paste del sitio de John.
Agradecimientos a John Wiley Spiers de antemano.
Actualización: Ahora para más informacion sobre los codigos de los productos, en Chile, recomiendo mi siguiente post:
El sistema armonizado y la clasificación arancelaria en Chile.