The URI specified using the standard url() pseudo-function may be resolved using XML catalogs.
For example, this feature can be used to customize the DocBook CSS style sheet bundled with XXE:
@import url(xxe-config:docbook/css/docbook.css);. .
my customization here.
This works because the XML catalog bundled with XXE, , contains the following rule:XXE_install_dir/addon/config/catalog.xml
<rewriteURI uriStartString="xxe-config:" rewritePrefix="." />