is permitted for regrowth of natural vegetation; conversely, where these conditions do not exist, the practice can have disastrous consequences for the environment.

Soil degradation - damage to the land's productive capacity because of poor agricultural practices such as the excessive use of pesticides or fertilizers, soil compaction from heavy equipment, or erosion of topsoil, eventually resulting in reduced ability to produce agricultural products.

Soil erosion - the removal of soil by the action of water or wind, compounded by poor agricultural practices, deforestation, overgrazing, and desertification.

Ultraviolet (UV) radiation - a portion of the electromagnetic energy emitted by the sun and naturally filtered in the upper atmosphere by the ozone layer; UV radiation can be harmful to living organisms and has been linked to increasing rates of skin cancer in humans. Water-born diseases - those in which bacteria survive in, and are transmitted through, water; always a serious threat in areas with an untreated water supply.

Environment - international agreements: This entry separates country participation in international environmental agreements into two levels - party to and signed, but not ratified. Agreements are listed in alphabetical order by the abbreviated form of the full name.

Environmental agreements: This information is presented in Appendix C: Selected International Environmental Agreements, which includes the name, abbreviation, date opened for signature, date entered into force, objective, and parties by category.

Ethnic groups: This entry provides an ordered listing of ethnic groups starting with the largest and normally includes the percent of total population.

Exchange rates: This entry provides the official value of a country's monetary unit at a given date or over a given period of time, as expressed in units of local currency per US dollar and as determined by international market forces or official fiat.

Executive branch: This entry includes several subfields. Chief of state includes the name and title of the titular leader of the country who represents the state at official and ceremonial functions but may not be involved with the day-to-day activities of the government. Head of government includes the name and title of the top administrative leader who is designated to manage the day-to-day activities of the government. For example, in the UK, the monarch is the chief of state, and the prime minister is the head of government. In the US, the president is both the chief of state and the head of government. Cabinet includes the official name for this body of high-ranking advisers and the method for selection of members. Elections includes the nature of election process or accession to power, date of the last election, and date of the next election. Election results includes the percent of vote for each candidate in the last election.

Exports: This entry provides the total US dollar amount of merchandise exports on an f.o.b. (free on board) basis. These figures are calculated on an exchange rate basis, i.e., not in purchasing power parity (PPP) terms.

Exports - commodities: This entry provides a rank ordering of exported products starting with the most important; it sometimes includes the percent of total dollar value.

Exports - partners: This entry provides a rank ordering of trading partners starting with the most important; it sometimes includes the percent of total dollar value.

Fiscal year: This entry identifies the beginning and ending months for a country's accounting period of 12 months, which often is the calendar year but which may begin in any month. All yearly references are for the calendar year (CY) unless indicated as a noncalendar fiscal year (FY).

Flag description: This entry provides a written flag description produced from actual flags or the best information available at the time the entry was written. The flags of independent states are used by their dependencies unless there is an officially recognized local flag. Some disputed and other areas do not have flags.

Flag graphic: Most versions of the Factbook include a color flag at the beginning of the country profile. The flag graphics were produced from actual flags or the best information available at the time of preparation. The flags of independent states are used by their dependencies unless there is an officially recognized local flag. Some disputed and other areas do not have flags.

GDP (official exchange rate): This entry gives the gross domestic product (GDP) or value of all final goods and services produced within a nation in a given year. A nation's GDP at offical exchange rates (OER) is the home-currency-denominated annual GDP figure divided by the bilateral average US exchange rate with that country in that year. The measure is simple to compute and gives a precise measure of the value of output. Many economists prefer this measure when gauging the economic power an economy maintains vis-a-vis its neighbors, judging that an exchange rate captures the purchasing power a nation enjoys in the international marketplace. Official exchange rates, however, can be artifically fixed and/or subject to manipulation - resulting in claims of the country having an under- or over-valued currency - and are not necessarily the equivalent of a market-determined exchange rate. Moreover, even if the official exchange rate is market-determined, market exchange rates are frequently established by a relatively small set of goods and services (the ones the country trades) and may not capture the value of the larger set of goods the country produces. Furthermore, OER-converted GDP is not well suited to comparing domestic GDP over time, since appreciation/depreciation from one year to the next will make the OER GDP value rise/fall regardless of whether home- currency-denominated GDP changed.

GDP (purchasing power parity): This entry gives the gross domestic product (GDP) or value of all final goods and services produced within a nation in a given year. A nation's GDP at purchasing power parity (PPP) exchange rates is the sum value of all goods and services produced in the country valued at prices prevailing in the United States. This is the measure most economists prefer when looking at per- capita welfare and when comparing living conditions or use of resources across countries. The measure is difficult to compute, as a US dollar value has to be assigned to all goods and services in the country regardless of whether these goods and services have a direct equivalent in the United States (for example, the value of an ox-cart or non-US military equipment); as a result, PPP estimates for some countries are based on a small and sometimes different set of goods and services. In addition, many countries do not formally participate in the World Bank's PPP project that calculates these measures, so the resulting GDP estimates for these countries may lack precision. For many developing countries, PPP-based GDP measures are multiples of the official exchange rate (OER) measure. The difference between the OER- and PPP- denominated GDP values for most of the weathly industrialized countries are generally much smaller.

GDP - composition by sector: This entry gives the percentage contribution of agriculture, industry, and services to total GDP. The distribution will total less than 100 percent if the data are incomplete.

GDP - per capita (PPP): This entry shows GDP on a purchasing power parity basis divided by population as of 1 July for the same year.

GDP - real growth rate: This entry gives GDP growth on an annual basis adjusted for inflation and expressed as a percent.

GDP methodology: In the Economy category, GDP