specification.md

@@ -81,3 +81,12 @@ NDL query is a Prolog like program, containing rules, with bodies consisting of
   * `swap_values(+Index1:variable_index, +Index2:variable_index)` - swap values of two variables
   * `flip_variable(+Index:variable_index, +HeadsValue:integer, +TailsValue:integer)` - if variable has value `HeadsValue` or `TailsValue`, sets the value to the other one. Otherwise fails.
 
+## Extensions
+
+There are several extensions to the NDL query, that can be used in order to increase the language expressiveness.
+
+### Stochastic mode
+
+NDL Queries can be compiled as stochastic operator. The stochastic mode impacts ordering of the `variable/(2..6)`, `constraint/3`, `range_element/2` results, effectively returning them in a random fashion. It does **not** impact `for_each` generator.
+
+**Warning:** stochastic ndl query always backtracks.