Since there are no script engine with XFA, the FormCalc parser is not used irl. The bug @nmtigor noticed was hidden by another one (the wrong check on `match`).
- the language specifications are: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.364.2157&rep=rep1&type=pdf#page=1049 - it can be used to: * as a scripting language for calculation, validations, ... * in SOM expressions to select nodes: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.364.2157&rep=rep1&type=pdf#page=101