Create README.md file

Convert the index.html file to Markdown file.

Author: jleffler

README.md

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+# BNF Grammars for SQL-92, SQL-99 and SQL-2003
+
+
+## SQL-92
+
+The file [`sql-92.bnf.html`](sql-92.bnf.html) is a heavily hyperlinked HTML
+version of the BNF grammar for SQL-92 (ISO/IEC 9075:1992 - Database Language -
+SQL).
+
+The plain text file [`sql-92.bnf`](sql-92.bnf), from which it was
+automatically converted, is more useful (read legible) for reading
+without a browser.
+
+## SQL-99
+
+The file [`sql-99.bnf.html`](sql-99.bnf.html) is a heavily hyperlinked HTML
+version of the BNF grammar for SQL-99 (ISO/IEC 9075-2:1999 - Database
+Languages - SQL - Part 2: Foundation (SQL/Foundation)).
+
+The plain text file [`sql-99.bnf`](sql-99.bnf), from which it was
+automatically converted, is more useful (read legible) for reading
+without a browser.
+
+## SQL-2003
+
+The file [`sql-2003-2.bnf.html`](sql-2003-2.bnf.html) is a heavily hyperlinked HTML
+version of the BNF grammar for SQL-2003 (ISO/IEC 9075-2:2003 - Database
+Languages - SQL - Part 2: Foundation (SQL/Foundation)).
+
+The plain text file [`sql-2003-2.bnf`](sql-2003-2.bnf), from which it was
+automatically converted, is more useful (read legible) for reading
+without a browser.
+
+
+There is a separate file [`sql-2003-1.bnf.html`](sql-2003-1.bnf.html) for
+the information from ISO/IEC 9075-1:2003 - Database Languages - SQL - Part
+1: Framework (SQL/Framework).
+
+It was automatically converted from the plain text file [`sql-2003-1.bnf`](sql-2003-1.bnf),
+which is more useful (read legible) for reading without a browser.
+
+
+Also available:
+<bl>
+<li> <a href="sql-2003-core-features.html"> SQL 2003 Core Features </a> </li>
+<li> <a href="sql-2003-noncore-features.html"> SQL 2003 Non-Core Features </a> </li>
+</bl>
+
+## Informix OUTER Join Syntax
+
+The file [`outer-joins.html`](outer-joins.html) is an explanation of the
+non-standar Informix OUTER join syntax and semantics.
+
+## Conversion tools
+
+
+The plain text was converted to HTML by the Perl script
+[`bnf2html`](bnf2html.perl.txt) which you may use if you wish.
+The `bnf2html` script also uses the C program
+WEBCODE version 1.09
+which you can download as a [gzipped tar file](webcode-1.09.tgz).
+
+See also [`bnf2yacc`](bnf2yacc.perl.txt), an experimental
+script to convert BNF into an outline Yacc grammar.
+The generated grammar typically includes some unacceptable tokens, such
+as _`%token 0`_, that should be handled by the lexical analyzer
+rather than the grammar.
+The SQL standard includes such rules as grammar rules; consequently, you won't
+get a clean Yacc grammar from the SQL BNF files.
+
+_(The Perl scripts should normally be renamed after downloading.)_
+
+## Download
+
+You can download a gzipped tar file containing the raw grammars, the
+HTML versions of those grammars, and the conversion tools as the gzipped
+tar file <a href="sql-bnf.tgz"> sql-bnf.tgz </a>.
+
+<hr>
+Please send feedback to Jonathan Leffler:
+<a href="mailto:jonathan.leffler@gmail.com"> jonathan.leffler@gmail.com </a>.
+
+Last modified:
+4th February 2017