Extend Countries_entity documentation

entity/Countries_Entity/documentation.adoc

 = Countries_Entity
 
+== Purpose
+
 The `Countries_Entity` is used for keeping information about the Countries of the world.
 It could be easily extend to hold information like:
 
@@ -10,5 +12,46 @@ It could be easily extend to hold information like:
 * spoken languages
 * etc
 
-The data origin is: https://chromium-i18n.appspot.com/ssl-address
-For more information, see: https://github.com/google/libaddressinput/wiki/AddressValidationMetadata at https://github.com/google/libaddressinput
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+== Data origin
+
+The data origins from several sources and is combined to one pool of information: 
+The underlying database table `AB_COUNTRYINFO`.
+
+The _alpha 2_ and _alpha 3_ codes (_ISO 3166_) are used to connect data between different sources.
+
+=== restcountries
+
+Source of data: https://restcountries.com/ or https://restcountries.eu/
+
+
+
+.Used for:
+* The base list of countries (=which countries are included)
+* NAME_LATIN
+* NAME_NATIVE
+* FLAG
+
+License: Mozilla Public License MPL 2.0
+
+=== google static data
+
+Source of data: https://chromium-i18n.appspot.com/ssl-address
+For more information, see: https://github.com/google/libaddressinput/wiki/AddressValidationMetadata at https://github.com/google/libaddressinput
+
+
+.Used for:
+* ADDR_FORMAT (with an additional separation for street and buildingnumber)
+* REQUIRED_FIELDS
+* ZIP_REGEX
+
+License: CC-BY 4.0
+
+=== Legacy ADITO Table
+
+Source of data: The database table for holding country information in the ADITO legacy-system.
+
+.Used for: 
+* Translations (these have been added to the languages)
+* Information for the order of the addressline
+** _Street_ _Buildingnumber_
+ ** _Buildingnumber_ _Street_
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