The data that shall be passed to the hook instance.
There are the following two types of data that can be specified: It is always possible to pass multiple data values for both data types, mapped and unmapped data. Multiple data definitions are separated with commas as you can see in the above examples.

Variable expansion
It is also possible to use a limited set of variables that will be expanded prior to the hook execution (exactly before the hook is executed).
Variables are referenced with @{VAR_NAME}.
Currently the implementation provides the following variables that can be used (but this is subject to change):