A Well-known Text represents a nested list of entities, with exactly one root entity. Each entity has a keyword in upper case followed by the defining, comma-delimited, parameters of the entity in brackets. The parameters can be strings, numbers, enumerations or other entities. While string, number and enumeration parameters are atomic building blocks of a WKT entity parameters will form a nested structure.
The basic syntax of a WKT is shown in listing 1. Square brackets [ ] can be substituted by standard brackets ( ), but either square or standard brackets must be used consistently within one WKT.
<entity> = <entity keyword>[<parameter>,{<parameter>}*]> <entity keyword> = Upper case alphanumeric string starting with a letter [A-Z] <parameter> = <string>|<number>|<enumeration value>|<entity> <string> Any text enclosed with ". The enclosed text must not contain a ". <number> = {+|-}{[0-9]}*{.<[0-9]>{<[0-9]>}* <enumeration value> = Upper case alphanumeric string starting with a letter [A-Z] containing no white space characters. |
Listing 1: Basic syntax of WKT
