Defines arbitrary variables with initial values. These variables may be loaded from a Java-style property file or set on plug-in import. Empty value is not supported: setting an empty value to a variable turns to clear the variable itself (it is no longer considered as defined). Similarly, getting a value from an undefined variable returns an empty string value. Any of these variables may be used in any plug-in parameter by referencing the variable through the following expression: ${this context plug-in identifier:variable's name}. Example: ${fooplugin:barvar} Remove all variable definitions. Duplicates a variable into a new variable with the same value. Set variables by loading a property file. Checks that the given variable is defined Checks that the given variable is not defined Sets a variable's value. Entering an empty value results in clearing the variable.