Mapping External Identifiers

The “public” and “system” entries map external identifiers to local resources based on public and/or system identifiers.

<public publicId="-//OASIS//DTD DocBook XML V4.2//EN"
        uri="/share/doctypes/docbook42/xml/docbookx.dtd"/>

<system systemId="http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
        uri="/share/doctypes/docbook42/xml/docbookx.dtd"/>