ADQL-2_1-Err-1 < IVOA

---+ ADQL 2.1 Erratum 1 : Addition of auxiliary files for the BNF grammar

*Author:* Grégory Mantelet

*Date last changed:* 2026-04-14

*Date accepted:* -
---++ Rationale

In ADQL-2.0 the BNF was provided only as an appendix of the ADQL document.

In ADQL-2.1, it is [[https://github.com/ivoa-std/ADQL/blob/master/adql.bnf][an external file]] that is included in place of the same appendix. [[https://github.com/ivoa-std/ADQL/blob/master/adql-bnf.html][An HTML version of this grammar]] is now also available. It allows a quicker navigation inside the grammar thanks to hyperlinks.

Currently, these two files are only available in the [[https://github.com/ivoa-std/ADQL/blob/master/adql-bnf.html][GitHub repository of ADQL]]. It was originally intented to make them also available in the IVOA Document Repository along the ADQL-2.1 Document. This erratum aims to add these auxiliary files and to add a clear link to them inside the document.
---++ Erratum Content

This erratum proposed to change two things:

   1 Add the following line in the Makefile in order to include the textual and HTML version of the BNF in the ADQL-2.1 release uploaded on the IVOA Document Repository: <verbatim>AUX_FILES = adql.bnf adql-bnf.html</verbatim>
   1 Change the title of the Appendix A in the ADQL-2.1 document from: <verbatim>\section{BNF grammar}</verbatim> into <verbatim>\appendix
\section[BNF grammar]{BNF grammar \footnote{
This entire BNF grammar is also available in two formats:
a \href{\currentDocURL/adql.bnf}{textual version} and
an \href{\currentDocURL/adql-bnf.html}{HTML version}.

}}</verbatim>
---++ Impact Assessment

With this erratum, nothing is changed in the ADQL-2.1 language.

Only links toward alternative BNF grammar formats are added.

No breaking change is expected on any existing client and server implementation.
---++ Notes

This erratum has been proposed in the GitHub Issue [[https://github.com/ivoa-std/ADQL/issues/78][#78]].

The HTML version of the BNF grammar has been generated using a Perl script created and distributed by [[mailto:jonathan.leffler@gmail.com][Jonathan Leffler]] on this [[https://github.com/ronsavage/SQL/blob/master/bnf2html.pl][third-party GitHub repository]] (see [[https://ronsavage.github.io/SQL/][the corresponding Website]]). This script is already included in the [[https://github.com/ivoa-std/ADQL][ADQL's GitHub repository]] and is already configured in the Makefile for an automatic generation.

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This topic: IVOA > WebHome > IvoaDAL > ADQL > ADQL-2_1-Errata > ADQL-2_1-Err-1
Topic revision: r1 - 2026-04-14 - GregoryMantelet