ICAO airport code

The ICAO (/ˌaɪˌkeɪˈoʊ/ eye-KAY-oh) airport code or location indicator is a four-letter code designating aerodromes around the world. These codes, as defined by the International Civil Aviation Organization and published in ICAO Document 7910: Location Indicators, are used by air traffic control and airline operations such as flight planning. ICAO codes are also used to identify other aviation facilities such as weather stations, international flight service stations or area control centers, whether or not they are

IATA airport code

An IATA airport code, also known as an IATA location identifier, IATA station code, or simply a location identifier, is a three-letter geocode designating many airports and metropolitan areas around the world, defined by the International Air Transport Association (IATA). The characters prominently displayed on baggage tags attached at airport check-in desks are an example of a way these codes are used. The assignment of these codes is governed by

Hydrological code

A hydrological code or hydrologic unit code is a sequence of numbers or letters that identify a hydrological feature like a river, river reach, lake, or area like a drainage basin (also called watershed in North America) or catchment. One system, developed by Strahler, known as the Strahler stream order, ranks streams based on a hierarchy of tributaries. Each segment of a stream or river within

House numbering

House numbering is the system of giving a unique number to each building in a street or area, with the intention of making it easier to locate a particular building. The house number is often part of a postal address. The term describes the number of any building (residential or commercial) with a mailbox, or even a

Hexadecimal

In mathematics and computing, the hexadecimal (also base 16 or hex) numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hexadecimal uses 16 distinct symbols, most often the symbols “0”–”9″ to represent values 0 to 9, and “A”–”F” (or alternatively “a”–”f”) to represent values from 10 to 15. Hexadecimal numerals are widely used

Hash function

A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. The values are usually used to index a fixed-size table called a hash table. Use of a hash function to index a hash table is called hashing or scatter storage addressing. Hash functions

Geotagging

Geotagging, or GeoTagging, is the process of adding geographical identification metadata to various media such as a geotagged photograph or video, websites, SMS messages, QR Codes or RSS feeds and is a form of geospatial metadata. This data usually consists of latitude and longitude coordinates, though they can also include altitude, bearing, distance, accuracy data, and place names, and perhaps a time stamp. Geotagging can help users find

Geohash

Geohash is a public domain geocode system invented in 2008 by Gustavo Niemeyer which encodes a geographic location into a short string of letters and digits. Similar ideas were introduced by G.M. Morton in 1966. It is a hierarchical spatial data structure which subdivides space into buckets of grid shape, which is one of the many applications of what is known as a Z-order

Finite set

In mathematics (particularly set theory), a finite set is a set that has a finite number of elements. Informally, a finite set is a set which one could in principle count and finish counting. For example, {\displaystyle \{2,4,6,8,10\}} is a finite set with five elements. The number of elements of a finite set is a natural number (a non-negative integer) and is called the cardinality of the set. A set that

Euclidean tilings by convex regular polygons

Euclidean plane tilings by convex regular polygons have been widely used since antiquity. The first systematic mathematical treatment was that of Kepler in his Harmonices Mundi (Latin: The Harmony of the World, 1619). Contents 1Notation of Euclidean tilings 2Regular tilings 3Archimedean, uniform or semiregular tilings 4k-uniform tilings 4.1Dissected regular polygons 4.22-uniform tilings 5Higher k-uniform tilings 5.1Fractalizing k-uniform tilings 5.1.1Fractalizing examples 6Tilings that are not edge-to-edge 7See also