JAPE is a finite state transducer that operates over annotations based on regular expressions.
Thus, it is useful for pattern-matching, semantic extraction, and many other operations over syntactic trees such as those produced by natural language parsers.
The phases run sequentially and constitute a cascade of finite state transducers over annotations.
Annotations matched on the LHS of a rule may be referred to on the RHS by means of labels that are attached to pattern elements.
Dhaval Thakker, Taha Osman, Phil Lakin, JAPE Grammar Tutorial, https://gate.ac.uk/sale/thakker-jape-tutorial/GATE%20JAPE%20manual.pdf