Explanatory Notes

Last updated June 6, 2018

Goods (Census basis)

Data for goods on a Census basis are compiled from the documents collected by U.S. Customs and
Border Protection (CBP) and reflect the movement of goods between foreign countries and the 50
states, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, and U.S. Foreign Trade
Zones. They include government and non-government shipments of goods and exclude shipments between
the United States and its territories and possessions; transactions with U.S. military, diplomatic,
and consular installations abroad; U.S. goods returned to the United States by its Armed Forces;
personal and household effects of travelers; and in-transit shipments. The General Imports value
reflects the total arrival of merchandise from foreign countries that immediately enters consumption
channels, warehouses, or Foreign Trade Zones.

For imports, the value reported is the CBP-appraised value of merchandise--generally, the price
paid for merchandise for export to the United States. Import duties, freight, insurance, and
other charges incurred in bringing merchandise to the United States are excluded. The exception
is Exhibit 17a, which shows CIF import value. The CIF (cost, insurance, and freight) value
represents the landed value of the merchandise at the first port of arrival in the United States.
It is computed by adding import charges to the customs value and therefore excludes U.S. import
duties.

Exports are valued at the f.a.s. (free alongside ship) value of merchandise at the U.S. port of
export, based on the transaction price including inland freight, insurance, and other charges
incurred in placing the merchandise alongside the carrier at the U.S. port of exportation.

Revision procedure (Census basis)

Monthly revisions: Monthly data include actual month's transactions as well as a small number of
transactions for previous months. Each month, the U.S. Census Bureau revises the aggregate
seasonally adjusted (current and real, or chained-dollar) and unadjusted export, import, and
trade balance figures, as well as the end-use totals for the prior month. Country detail data
and commodity detail data, based on the Standard International Trade Classification (SITC) Revision
4 and the North American Industry Classification System (NAICS), are not revised monthly. The
timing adjustment shown in Exhibit 14 is the difference between monthly data as originally reported
and as recompiled.

For March, unadjusted exports of goods were revised up $0.1 billion and unadjusted imports of
goods were revised up less than $0.1 billion. Goods carry-over in April was $0.1 billion
(0.1 percent) for exports and $0.1 billion (0.1 percent) for imports. For March, revised export
carry-over was less than $0.1 billion (less than 0.1 percent) and revised import carry-over was
less than $0.1 billion (less than 0.1 percent).

Quarterly revisions to chain-weighted dollar series: For March, June, September, and December
statistical month releases, revisions are made to the real, or chained-dollar, series presented
in Exhibits 10 and 11: the previous five months are revised to incorporate the U.S. Bureau of
Labor Statistics' (BLS) revisions to price indexes, which are used to produce the real series
and to align Census data with data published by the U.S. Bureau of Economic Analysis (BEA) in
the national income and product accounts (NIPAs).

Annual revisions: Each June, not seasonally adjusted goods data are revised to redistribute
monthly data that arrived too late for inclusion in the month of transaction. In addition,
revisions are made to reflect corrections received subsequent to the monthly revisions. Seasonally
adjusted data are also revised to reflect recalculated seasonal and trading-day adjustments.
These revisions are reflected in totals, end-use, commodity, and country summary data.

Other revisions: For December and January statistical month releases, each prior month of the
most recent full year is revised so that the totals of the seasonally adjusted months equal the
annual totals.

U.S./Canada data exchange and substitution

Data for U.S. exports to Canada are derived from import data compiled by Canada. The use of
Canada's import data to produce U.S. export data requires several alignments in order to compare
the two series.

1. Coverage - Canadian imports are based on country of origin. U.S. goods shipped from a third
   country are included. U.S. exports exclude these foreign shipments. For April 2018, these
   shipments totaled $163.4 million. U.S. export coverage also excludes U.S. postal shipments
   to Canada. For April 2018, these shipments totaled $25.3 million.

   U.S. import coverage includes shipments of railcars and locomotives from Canada. Effective
   with January 2004 statistics, Canada excludes these shipments from its goods exports to the
   United States, therefore creating coverage differences between the two countries for these
   goods.
2. Valuation - Canadian imports are valued at the point of origin in the United States. However,
   U.S. exports are valued at the port of exit in the United States and include inland freight
   charges, making the U.S. export value slightly larger than the Canadian import value. Canada
   requires inland freight to be reported separately from the value of the goods. Combining the
   inland freight and the Canadian reported import value provides a consistent valuation for all
   U.S. exports. Inland freight charges for April 2018 accounted for 1.9 percent of the value of
   U.S. exports to Canada.
3. Re-exports - Unlike Canadian imports, which are based on country of origin, U.S. exports
   include re-exports of foreign goods. Therefore, the aggregate U.S. export figure is slightly
   larger than the Canadian import figure. For April 2018, re-exports to Canada were $4,220.6
   million.
4. Exchange Rate - Average monthly exchange rates are applied to convert the published data to
   U.S. currency. For April 2018, the average exchange rate was 1.2732 Canadian dollars per U.S.
   dollar.
5. Other - There are other minor differences, such as rounding error, that are statistically
   insignificant.

Canadian estimates: Effective with January 2001 statistics, the current month data for exports
to Canada contain an estimate for late arrivals and corrections. In the following month, this
estimate is replaced, in the news release exhibits only, with the actual value of late receipts
and corrections. This estimate improves the current month data for exports to Canada and treats
late receipts for exports to Canada in a manner that is more consistent with the treatment of
late receipts for exports to other countries.

Nonsampling errors

The goods data are a complete enumeration of documents collected by CBP and are not subject to
sampling errors. Quality assurance procedures are performed at every stage of collection,
processing, and tabulation. However, the data are still subject to several types of nonsampling
errors. The most significant of these include reporting errors, undocumented shipments, timeliness,
data capture errors, and errors in the estimation of low-valued transactions.

Reporting errors: Reporting errors are mistakes or omissions made by importers, exporters, or
their agents in their import or export declarations. Most errors involve missing or invalid
commodity classification codes and missing or incorrect quantities or shipping weights. They have
a negligible effect on aggregate import, export, and balance of trade statistics. However, they
can affect the detailed commodity statistics.

Undocumented shipments: Federal regulations require importers, exporters, or their agents to
report all merchandise shipments above established exemption levels. The Census Bureau has
determined that not all required documents are filed, particularly for exports.

Timeliness and data capture errors: The Census Bureau captures import and export information
from administrative documents and through various automated collection programs. Documents may
be lost, and data may be incorrectly keyed, coded, or recorded. Transactions may be included in
a subsequent month's statistics if received late.

Low-valued transactions: The total values of transactions valued as much as or below $2,500 for
exports and $2,000 ($250 for certain quota items) for imports are estimated for each country,
using factors based on the ratios of low-valued shipments to individual country totals for past
periods.

The Census Bureau recommends that data users incorporate this information into their analyses,
as nonsampling errors could impact the conclusion drawn from the results. See "U.S. Merchandise
Trade Statistics: A Quality Profile (www.census.gov/foreign-trade/aip/quality_profile10032014.pdf)" 
(October 2014) for a detailed discussion of errors affecting the goods data.

Area groupings

North America: Canada, Mexico.

Dominican Republic-Central America-United States Free Trade Agreement (CAFTA-DR): Costa Rica,
Dominican Republic, El Salvador, Guatemala, Honduras, Nicaragua.

Europe: Albania, Andorra, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bosnia and Herzegovina,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Faroe Islands, Finland, France,
Georgia, Germany, Gibraltar, Greece, Hungary, Iceland, Ireland, Italy, Kazakhstan, Kosovo,
Kyrgyzstan, Latvia, Liechtenstein, Lithuania, Luxembourg, Macedonia, Malta, Moldova, Monaco,
Montenegro, Netherlands, Norway, Poland, Portugal, Romania, Russia, San Marino, Serbia, Slovakia,
Slovenia, Spain, Svalbard-Jan Mayen Island, Sweden, Switzerland, Tajikistan, Turkey, Turkmenistan,
Ukraine, United Kingdom, Uzbekistan, Vatican City.

European Union: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom.

Euro Area: Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Portugal, Slovakia, Slovenia, Spain.

Pacific Rim: Australia, Brunei, China, Hong Kong, Indonesia, Japan, Korea (South), Macau, Malaysia,
New Zealand, Papua New Guinea, Philippines, Singapore, Taiwan.

South/Central America: Anguilla, Antigua and Barbuda, Argentina, Aruba, Bahamas, Barbados, Belize,
Bermuda, Bolivia, Brazil, British Virgin Islands, Cayman Islands, Chile, Colombia, Costa Rica,
Cuba, Curacao, Dominica, Dominican Republic, Ecuador, El Salvador, Falkland Islands (Islas Malvinas),
French Guiana, Grenada, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique,
Montserrat, Netherlands Antilles, Nicaragua, Panama, Paraguay, Peru, Sint Maarten, St. Kitts and
Nevis, St. Lucia, St. Vincent and the Grenadines, Suriname, Trinidad and Tobago, Turks and Caicos
Islands, Uruguay, Venezuela.

Organization of Petroleum Exporting Countries (OPEC): Algeria, Angola, Ecuador, Equatorial Guinea,
Gabon, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, Venezuela.

Africa: Algeria, Angola, Benin, Botswana, British Indian Ocean Territories, Burkina Faso, Burundi,
Cabo Verde, Cameroon, Central African Republic, Chad, Comoros, Congo (Brazzaville), Congo (Kinshasa),
Djibouti, Egypt, Equatorial Guinea, Eritrea, Ethiopia, French Southern and Antarctic Lands, Gabon,
Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Kenya, Lesotho, Liberia, Libya, Madagascar,
Malawi, Mali, Mauritania, Mauritius, Mayotte, Morocco, Mozambique, Namibia, Niger, Nigeria,
Reunion, Rwanda, St. Helena, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, Somalia,
South Africa, South Sudan, Sudan, Swaziland, Tanzania, Togo, Tunisia, Uganda, Western Sahara,
Zambia, Zimbabwe.

Adjustments for seasonal and trading-day variations

Goods are initially classified under the Harmonized Commodity Description and Coding System
(Harmonized System), which is an internationally accepted standard for the commodity classification
of traded goods. The Harmonized System describes and measures the characteristics of the goods
and is the basis for the systems used in the United States: Schedule B for exports and Harmonized
Tariff Schedule for imports. Combining trade into approximately 140 export and 140 import end-
use categories makes it possible to examine goods according to their principal uses (see Exhibits
7 and 8). These categories are used as the basis for computing the seasonal and trading-day
adjusted data. These adjusted data are then summed to the six end-use aggregates for publication
(see Exhibit 6). The Census Bureau provides these data to BEA for use in the NIPAs and in the
U.S international transactions accounts (balance of payments accounts).

Exhibit 19 shows goods (Census basis) that are seasonally adjusted for selected countries and
world areas. Unlike the commodity-based adjustments discussed above, these adjustments are
developed and applied directly at the country and world area levels. For total exports and imports,
data users should refer to the commodity-based totals shown in the other exhibits. The seasonally
adjusted country and world area data will not sum to the seasonally adjusted commodity-based
totals because the seasonally adjusted country and world area data and the commodity-based totals
are derived from different aggregations of the export and import data and from different seasonal
adjustment models. Data users should use caution drawing comparisons between the two sets of
seasonally adjusted series.

The seasonal adjustment procedure (X13-ARIMA-SEATS) is based on a model that estimates the monthly
movements as percentages above or below the general level of series (unlike other methods that
redistribute the actual series values over the calendar year). Because the data series for aircraft
is highly variable, users studying data trends may wish to analyze trade in aircraft separately
from other trade.

Adjustments for price change

Data adjusted for seasonal variation on a real, or chained-dollar, basis (2012 reference year)
are presented in Exhibits 10 and 11. This adjustment for price change is done using the Fisher
chain-weighted methodology. The deflators are primarily based on the monthly price indexes
published by the BLS using techniques developed for the NIPAs by BEA.

Principal commodities

Goods data appearing in Exhibit 15 are classified in terms of the SITC Revision 4, with the
exception of agricultural and manufactured goods. Agricultural goods are defined by the U.S.
Department of Agriculture (USDA); they consist of non-marine food products and other products of
agriculture that have not passed through complex processes of manufacture. Manufactured goods
conform to the NAICS; they consist of goods that have been mechanically, physically, or chemically
transformed. USDA agricultural goods and NAICS manufactured goods are not mutually exclusive
categories.

Re-exports are foreign merchandise entering the country as imports and then exported in substantially
the same condition as when imported. Re-exports, which are included in overall export totals,
appear as separate line items in Exhibit 15.

Advanced technology products

About 500 of some 22,000 Schedule B and Harmonized Tariff Schedule classification codes used in
reporting U.S. merchandise trade are identified as "advanced technology" codes, and they meet
the following criteria:

1. The code contains products whose technology is from a recognized high technology field
   (e.g., biotechnology).
2. These products represent leading edge technology in that field.
3. Such products constitute a significant part of all items covered in the selected classification
   code.

The aggregation of the goods results in a measure of advanced technology trade that appears in
Exhibits 16 and 16a. This product- and commodity-based measure of advanced technology differs
from broader NAICS-based measures, which include all goods produced by a particular industry
group, regardless of the level of technology embodied in the goods.

Goods (balance of payments basis) and services

Quarterly and annual statistics for goods on a balance of payments (BOP) basis and for services
are included in the U.S. international transactions accounts (ITAs), which are published by BEA
in news releases in March, June, September, and December and in the Survey of Current Business (www.bea.gov/scb/index.htm)
in the January, April, July, and October issues. The next release of the ITAs is scheduled for
June 20, 2018.

In addition, BEA releases detailed annual international services (www.bea.gov/iTable/iTable.cfm?reqid=62&step=9&isuri=1&6210=4#reqid=62&step=9&isuri=1&6210=4) statistics, which consist of
statistics on trade in services and on services supplied through affiliates of multinational
enterprises. The statistics provide detail on U.S. trade in services by type and by country and
area and detail on services supplied through affiliates by industry and by country and area.

Goods (balance of payments basis)

Goods on a Census basis are adjusted by BEA to a BOP basis to align the data with the concepts
and definitions used to prepare the international and national economic accounts. These adjustments,
which are applied separately to exports and imports, are necessary to supplement coverage of
the Census data, to eliminate duplication of transactions recorded elsewhere in the international
accounts, and to value transactions at market prices. They include both additions to and deductions
from goods on a Census basis and are presented in this release as net adjustments. Adjustments
that exhibit significant seasonal patterns are seasonally adjusted. BEA also publishes more
detailed quarterly and annual statistics for net adjustments in ITA Table 2.4. U.S. International
Trade in Goods, Balance of Payments Adjustments (www.bea.gov/iTable/iTableHtml.cfm?reqid=62&step=6&isuri=1&6210=1&6200=48) and in the January, April, July, and October
issues of the Survey of Current Business.

The export adjustments include:

   Gold exports, nonmonetary - This addition is made for gold that is purchased by foreign official
   agencies from private dealers in the United States and held at the Federal Reserve Bank of
   New York. The Census data only include gold that leaves the U.S. customs territory.

   Goods procured in U.S. ports by foreign carriers - This addition is made for foreign air and
   ocean carriers' fuel purchases in U.S. ports.

   Net exports of goods under merchanting - This addition is made to include the net value of
   the purchase and subsequent resale of goods abroad without the goods entering the United
   States. Because these goods do not cross the U.S. customs frontier, their value is not recorded
   in the Census data.

   Other adjustments to exports include:

   Deductions for equipment repairs (parts and labor), developed motion picture film, military
   grant-aid, and, for periods prior to 2010, goods identified in the Census data as exports
   under the Foreign Military Sales (FMS) program. Additions for sales of fish caught in U.S.
   territorial waters, exports of electricity to Mexico, private gift parcels, vessels and oil
   rigs for which ownership changes, valuation of software exports at market value, low-value
   (below reporting threshold) transactions for 1999-2009 to phase in a revised Census Bureau
   low-value methodology that was implemented for goods on a Census basis beginning with statistics
   for 2010, and, for periods prior to 2010, FMS goods exports reported to BEA by the U.S.
   Department of Defense.

The import adjustments include:

   Gold imports, nonmonetary - This addition is made for gold sold by foreign official agencies
   to private purchasers out of stock held at the Federal Reserve Bank of New York. The Census
   data only include gold that enters the U.S. customs territory.

   Goods procured in foreign ports by U.S. carriers - This addition is made for U.S. air and
   ocean carriers' fuel purchases in foreign ports.

   Imports by U.S. military agencies - This addition is made for purchases of goods abroad by
   U.S. military agencies, which are reported to BEA by the Department of Defense. The Census
   data only include imports of goods by U.S. military agencies that enter the U.S. customs
   territory.

   Inland freight in Canada and Mexico - This addition is made for inland freight in Canada and
   Mexico. Imports of goods from all countries should be valued at the customs value--the value
   at the foreign port of export including inland freight charges. For imports from Canada and
   Mexico, this should be the cost of the goods at the U.S. border. However, the customs value
   for imports for certain Canadian and Mexican goods is the point of origin in Canada or Mexico.
   BEA makes an addition for the inland freight charges of transporting these goods to the U.S.
   border to make the value comparable to the customs value reported for imports from other
   countries.

   Other adjustments to imports include:

   Deductions for equipment repairs (parts and labor), repairs to U.S. vessels abroad, and
   developed motion picture film.  Additions for non-reported imports of locomotives and railcars,
   imports of electricity from Mexico, conversion of vessels for commercial use, valuation of
   software imports at market value, and low-value (below reporting threshold) transactions for
   1999-2009 to phase in a revised Census Bureau low-value methodology that was implemented for
   goods on a Census basis beginning with statistics for 2010.

Services

The services statistics cover transactions between foreign countries and the 50 states, the
District of Columbia, Puerto Rico, the U.S. Virgin Islands, and other U.S. territories and
possessions. Transactions with U.S. military, diplomatic, and consular installations abroad are
excluded because these installations are considered to be part of the U.S. economy.

Services statistics are based on quarterly, annual, and benchmark surveys and information obtained
from monthly government and industry reports. For categories for which monthly data are not
available, monthly statistics are derived from quarterly statistics through temporal distribution,
or interpolation. The interpolation methodology used by BEA is the modified Denton proportional
first difference method. This method preserves the pattern of the monthly indicator series, if
available, while satisfying the annual aggregation constraints. See "An Empirical Review of
Methods for Temporal Distribution and Interpolation in the National Accounts 
(www.bea.gov/scb/pdf/2008/05%20May/0508_methods.pdf)" (May 2008) for more information. Services are 
seasonally adjusted when statistically significant seasonal patterns are present.

Services are shown in nine broad categories. The following is a brief description of the types
of services included in each category:

   Maintenance and repair services n.i.e. (not included elsewhere) - Consists of maintenance and
   repair services performed by residents of one country on goods that are owned by residents of
   another country. The repairs may be performed at the site of the repair facility or elsewhere.
   Excludes such services in which the cost is included in the price of the goods and is not
   billed separately or is declared as a part of the price of the goods on the import or export
   declaration filed with the U.S. Customs and Border Protection. Maintenance and repair of
   computers are included under computer services, and some maintenance and repair of ships,
   aircraft, and other transport equipment are included under transport services.

   Transport - Consists of transactions associated with moving people and freight from one location
   to another and includes related supporting and auxiliary services. Transport covers all modes
   of transportation, including air, sea, rail, road, space, and pipeline. Postal and courier
   services and port services, which cover cargo handling, storage and warehousing, and other
   related transport services, are also included.

   Travel (for all purposes including education) - Includes goods and services acquired by
   nonresidents while abroad. A traveler is defined as a person who stays, or intends to stay,
   for less than one year in a country of which he or she is not a resident or as a nonresident
   whose purpose is to obtain education or medical treatment, no matter how long the stay.
   Purchases can be either for own use or for gifts to others. Travel is a transactor-based
   component that covers a variety of goods and services, primarily lodging, meals, transportation
   in the country of travel, amusement, entertainment, and gifts. Travel excludes air passenger
   services for travel between countries, which are included in transport, and goods for resale,
   which are included in goods.

   Travel includes business and personal travel. Business travel covers goods and services acquired
   for use by persons whose primary purpose for travel is for business (including goods and
   services for which business travelers are reimbursed by employers). Business travel also
   includes expenditures by border, seasonal, and other short-term workers in their economy of
   employment. Personal travel covers travel for all non-business purposes, including for medical
   or educational purposes.

   Insurance services - Includes the direct insurance services of providing life insurance and
   annuities, non-life (property and casualty) insurance, reinsurance, freight insurance, and
   auxiliary insurance services.  Insurance is measured as gross premiums earned plus premium
   supplements less claims payable, with an adjustment for claims volatility. Premium supplements
   represent investment income from insurance reserves, which are attributed to policyholders
   who are treated as paying the income back to the insurer. Auxiliary insurance services include
   agents' commissions, brokerage services, insurance consulting services, actuarial services,
   and other insurance services.

   Financial services - Includes financial intermediary and auxiliary services, except insurance
   services. These services include those normally provided by banks and other financial
   institutions. Services primarily include those for which an explicit commission or a fee is
   charged; implicit fees for bond transactions, measured as the difference between bid and ask
   prices, are also included. Services include securities brokerage and underwriting, financial
   management, financial advisory, and custody services; credit and other credit-related services;
   and securities lending, electronic funds transfer, and other services.

   Charges for the use of intellectual property n.i.e. - Includes charges for the use of proprietary
   rights, such as patents, trademarks, and copyrights, and charges for licenses to use, reproduce,
   distribute, and sell or purchase intellectual property.

   Telecommunications, computer, and information services - Telecommunications services include
   the broadcast or transmission of sound, images, data, or other information by electronic means.
   These services do not include the value of the information transmitted. Computer services
   consist of hardware- and software-related services and data processing services. Sales of
   customized software and related use licenses, as well as licenses to use non-customized software
   with a periodic license fee, are also included, as is software downloaded or otherwise
   electronically delivered. Cross-border transactions in non-customized packaged software with
   a license for perpetual use are included in goods. Information services include news agency
   services, database services, and web search portals.

   Other business services - Consists of research and development services, professional and
   management consulting services, and technical, trade-related, and other business services.
   Research and development services include services associated with basic and applied research
   and experimental development of new products and processes. Professional and management
   consulting services include legal services, accounting, management consulting, managerial
   services, public relations services, advertising, and market research. Amounts received by a
   parent company from its affiliates for general overhead expenses related to these services
   are included. Technical, trade-related, and other business services include architectural and
   engineering, construction, audio-visual, waste treatment, operational leasing, trade-related,
   and other business services.

   Government goods and services n.i.e. - Includes goods and services supplied by and to enclaves,
   such as embassies, military bases, and international organizations; goods and services acquired
   from the host economy by diplomats, consular staff, and military personnel located abroad and
   their dependents; and services supplied by and to governments that are not included in other
   services categories. Services supplied by and to governments are classified to specific services
   categories when source data permit.

Goods (BOP basis) and services by country and area

Monthly country and area detail is not available for goods on a BOP basis or for services. However,
quarterly statistics on goods on a BOP basis and on services that are seasonally adjusted by
geography are shown in Exhibit 20. Unlike the seasonal adjustments by commodity and by service
type that are applied to the global totals, these adjustments are developed and applied directly
at the country and world area levels. For total exports and imports, data users should refer to
the by-commodity and by-service type totals shown in the other exhibits. The seasonally adjusted
country and world area data will not sum to the seasonally adjusted by-commodity and by-service
type totals because the two sets of statistics are derived from different aggregations of the
export and import data and from different seasonal adjustment models. Data users should use
caution drawing comparisons between the two sets of seasonally adjusted series.

The definitions of the world areas shown in Exhibit 20 are consistent with the definitions for
goods on a Census basis (see AREA GROUPINGS above) with a few exceptions. For services, CAFTA-DR
is not available because trade with this area's member countries cannot be separately identified.
For goods on a BOP basis and for services, European Union and OPEC reflect the composition of
the areas at the time of reporting.

Revision procedure (goods on a BOP basis and services)

Monthly revisions: Each month, a preliminary estimate for the current month and a revised estimate
for the immediately preceding month are released. After the initial revision, no further revisions
are made to a month until more complete source data become available in March, June, September,
and December.

Quarterly revisions: The releases in March, June, September, and December contain revised estimates
for the previous six months to incorporate more comprehensive and updated source data.

Annual revisions: Each June, historical data are revised to incorporate newly available and
revised source data, changes in definitions and classifications, and changes in estimation methods.
Seasonally adjusted data are also revised to reflect recalculated seasonal and trading-day
adjustments.

Other revisions: The release in February contains revisions to goods for January through November
of the most recent year; the release in March contains revisions to both goods and services for
all months of the most recent year. These revisions result from forcing the seasonally adjusted
months to equal the annual totals.

Data availability

The U.S. International Trade in Goods and Services news release (FT-900) and the FT-900 Supplement
are available at www.census.gov/ft900 or www.bea.gov/newsreleases/international/trade/tradnewsrelease.htm.

Census Bureau's application programming interface (API): The Census Bureau's API, available at
www.census.gov/developers/, lets developers create custom apps to reach new users and makes key
demographic, socio-economic, and housing statistics more accessible than ever before.

BEA's data API: BEA's data API, available at www.bea.gov/API/signup/index.cfm, provides programmatic
access to BEA's published economic statistics using industry-standard methods and procedures.