### 10.4 XML/SGML requirements ¶

Festival is distributed with `rxp` an XML parser developed by Richard Tobin of the Language Technology Group, University of Edinburgh. Sable is set up as an XML text mode so no further requirements or external programs are required to synthesize from Sable marked up text (unlike previous releases). Note that `rxp` is not a full validation parser and hence doesn’t check some aspects of the file (tags within tags).

Festival still supports SGML based markup but in such cases requires an external SGML normalizing parser. We have tested `nsgmls-1.0` which is available as part of the SGML tools set `sp-1.1.tar.gz` which is available from http://www.jclark.com/sp/index.html. This seems portable between many platforms.