Short answers, pulled from the story.
SYNTAX is a system used to generate lexical and syntactic analyzers, also called parsers, for all kinds of context-free grammars as well as some classes of contextual grammars. It produces both deterministic and non-deterministic analyzers.
SYNTAX was developed at INRIA in France over several decades, mostly by Pierre Boullier.
SYNTAX became free software in 2007 and is distributed under the CeCILL license.
SYNTAX handles deterministic, unambiguous grammars such as LR, LALR, and RLR, along with general context-free grammars. Its non-deterministic features include an Earley parser generator used for natural language processing.
SYNTAX includes a built-in algorithm that automatically recovers from lexical and syntactic errors by deleting extra characters or tokens, inserting missing ones, or permuting characters or tokens. Its default behaviour can be modified with a custom set of recovery rules adapted to the target language.
Beyond the domain of compilation, where its deterministic version has been used in operational contexts such as Ada, SYNTAX version 6.0 beta includes parser generators for context-sensitive formalisms such as TAG, RCG, and LFG, used for natural language processing and bio-informatics.