Extraction engines query the context; transformation engines bind it
The engines an author can choose split into two families, and the split decides what the surrounding data means to the expression they write.
The rule
Normative: this is the rule
- An extraction engine treats the evaluation context as data to be queried by a path.
- A transformation engine treats the same context as a map of variables the expression may reference by name.
Rule identifiers are permanent and are never renumbered. Each implementation publishes its own standing against these rules; this specification does not.spec 1.0-draft · LANG-1 · changed in spec 1.0