anchor.diff:  Open Post Codes have an optional checksum that can be used to distinguish
   the country a code was generated for.
   
  -== link:http://nacgeo.com[Natural Area Code]
  -
  -Natural Area Code is a proprietary system that requires licenses to use
  +== Natural Area Code
  +
  +Natural Area Code <<nac-site>> is a proprietary system that requires licenses to use
   <<naclicense>>. The codes are made up of up to three parts, the first
   provides the latitude, the second the longitude and an optional third part
   the altitude as the arctangent of the altitude relative to the Earth's
  
positive.code: cyrillic "НН.НН". Open Location Code currently only supports a Latin
  character set.
  
  == link:http://openpostcode.org[Open Post Code]
  
  Open Post Codes can be defined globally or within a containing country
  <<openpostcode>>. The global codes are a similar length to Open Location
  Codes, but codes defined within a country are shorter than full Open
  Location Codes, and a similar length to short Open Location Codes.
  
  Four countries are defined: Ireland, Hong Kong, Yemen and India.
  
  Every location on the planet has a global code. Locations within the
  countries where Open Post Code has been defined also have a local code.
  
negative.code: The Geohash-36 definition includes an optional altitude specification, and
  an optional checksum, neither of which are provided by Open Location Code.
  
  == MapCode
  
  MapCodes can be defined globally or within a containing territory
  <<mapcode>>. The global codes are a similar length to Open Location Codes,
  