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 an external file that is included in place of the same appendix. 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 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:

   AUX_FILES = adql.bnf adql-bnf.html

2. Change the title of the Appendix A in the ADQL-2.1 document from:

   \section{BNF grammar}

   into

   \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}.
   
   }}

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 #78.

The HTML version of the BNF grammar has been generated using a Perl script created and distributed by Jonathan Leffler on this third-party GitHub repository (see the corresponding Website). This script is already included in the ADQL's GitHub repository and is already configured in the Makefile for an automatic generation.

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