Wirth syntax notation

Wirth syntax notation (WSN) is a metasyntax, that is, a formal way to describe formal languages. Originally proposed by Niklaus Wirth in 1977 as an alternative to Backus–Naur form (BNF). It has several advantages over BNF in that it contains an explicit iteration construct, and it avoids the use of an explicit symbol for the empty string (such as <empty> or ε).[1]

WSN has been used in several international standards, starting with ISO 10303-21.[2] It was also used to define the syntax of EXPRESS, the data modelling language of STEP.

  1. ^ Wirth, Niklaus (November 1977). "What Can We Do about the Unnecessary Diversity of Notations for Syntax Definitions?". Communications of the ACM. 20 (11): 822–823. doi:10.1145/359863.359883. S2CID 35182224.
  2. ^ "ISO 10303-21, Industrial automation systems and integration — Product data representation and exchange — Part 21: Implementation methods: Clear text encoding of the exchange structure". International Organization for Standardization. 24 January 2002. {{cite journal}}: Cite journal requires |journal= (help)[dead link]