libxmlada-schema12-dev binary package in Ubuntu Mantic arm64

 XML/Ada is a set of modules that provide a simple manipulation of XML
 streams. It supports the whole XML 1.0 specifications, and can parse
 any file that follows this standard (including the contents of the
 DTD). It also provides support for a number of other standard
 associated with XML, like SAX, DOM, and XML Schemas. In addition, it
 includes a module to manipulate Unicode streams, since this is required
 by the XML standard.
 .
 This package contains the development tools for the schema module,
 and an xmlada.gpr project importing the whole XML/Ada library.

Source package