The mandatory node has 100% probability and will be included in all produced documents. It is default kind of node.
The node can be generated once or more times in the range provided by the user by specifying "Repeat-to" values.
The user allowed specifying some repeat value as well as 0 for "data driven" repeating counter. In this case, data will define a number of nodes to be generated. For example, if $File function returns 10 rows, the generator will repeat associated node 10 times.