cludes heliports limited to day
operations and natural clearings that could support helicopter landings
and takeoffs.

Highways
This entry states the total length of the highway system and the length
of the paved and unpaved parts.

Household income or consumption by percentage share
Data on household income or consumption come from household surveys,
the results adjusted for household size. Nations use different
standards and procedures in collecting and adjusting the data. Surveys
based on income will normally show a more unequal distribution than
surveys based on consumption. The quality of surveys is improving with
time, yet caution is still necessary in making inter-country
comparisons.

Hydrographic data codes
see Data codes

Illicit drugs
This entry gives information on the five categories of illicit drugs -
narcotics, stimulants, depressants (sedatives), hallucinogens, and
cannabis. These categories include many drugs legally produced and
prescribed by doctors as well as those illegally produced and sold
outside of medical channels.
Cannabis (Cannabis sativa) is the common hemp plant, which provides
hallucinogens with some sedative properties, and includes marijuana
(pot, Acapulco gold, grass, reefer), tetrahydrocannabinol (THC,
Marinol), hashish (hash), and hashish oil (hash oil).
Coca (mostly Erythroxylum coca) is a bush with leaves that contain the
stimulant used to make cocaine. Coca is not to be confused with cocoa,
which comes from cacao seeds and is used in making chocolate, cocoa,
and cocoa butter.
Cocaine is a stimulant derived from the leaves of the coca bush.
Depressants (sedatives) are drugs that reduce tension and anxiety and
include chloral hydrate, barbiturates (Amytal, Nembutal, Seconal,
phenobarbital), benzodiazepines (Librium, Valium), methaqualone
(Quaalude), glutethimide (Doriden), and others (Equanil, Placidyl,
Valmid).
Drugs are any chemical substances that effect a physical, mental,
emotional, or behavioral change in an individual.
Drug abuse is the use of any licit or illicit chemical substance that
results in physical, mental, emotional, or behavioral impairment in an
individual.
Hallucinogens are drugs that affect sensation, thinking, self-
awareness, and emotion. Hallucinogens include LSD (acid, microdot),
mescaline and peyote (mexc, buttons, cactus), amphetamine variants
(PMA, STP, DOB), phencyclidine (PCP, angel dust, hog), phencyclidine
analogues (PCE, PCPy, TCP), and ot