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Comments, Queries, and Debate: What Does BNF Stand for? Disclosure Number: IPCOM000129646D
Original Publication Date: 1990-Dec-31
Included in the Prior Art Database: 2005-Oct-06
Document File: 2 page(s) / 16K

Publishing Venue

Software Patent Institute

Related People

Mike Woodger: AUTHOR [+2]


10 Ottways Lane Ashtead, Surrey K721 2NZ England

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Copyright ©; 1990 by the American Federation of Information Processing Societies, Inc. Used with permission.

Comments, Queries, and Debate: What Does BNF Stand for?

Mike Woodger

10 Ottways Lane Ashtead, Surrey K721 2NZ England

Paragraph 4 of Section 1.5 of the standard reference manual for the Ada programming language states: "The context-free syntax of the language is described using a simple variant of Backus Naur Form."

During the canvas process, when this text was under scrutiny as an ANSI standard (1982), one of the critics suggested that it should read "Backus Normal Form." It fell to me LO defend the present text.

There are two sides to this: Why "normal," anyway? And why "Naur"?

My main complaint is the utter inappropriateness of "normal" in this case. Backus did not imply that his was one of a number of possible notations selectable in any sense as a "norm," nor did he refer to any normalization process. He in fact reinvented a form already described by N. Chomsky. I do not know who first used the phrase "Backus Normal Form," but it is clear that he did not have any authority to use it -- and everybody else just copied, the way they do!

Someone who was there informed me that, when John Backus and Peter Naur met at the ACM S IGPLAN History of Programming Languages Conference held in Los Angeles on 1-3 June 1978, Peter finally repudiated the reading of N in BNF as "Naur" rather than "normal." The record is rather different. (I am indebted to Peter Naur for sending me photocopies11.)

In December 1964, Donald Knuth wrote to the editor of the Communications of the ACM objecting to the terminology "Backus Normal Form" on much the same grounds as I do. He quoted a survey by S. Gorn as the earliest use of the term that he could remember and proposed the reading "Backus Naur Form" to honor the contribution of Naur. He explain...