Core Methods
From Documentation
In this section we describe the EL functions defined in the built-in TLD called http://www.zkoss.org/dsp/web/core.
For example,
<?taglib uri="http://www.zkoss.org/dsp/web/core" prefix="c"?>
<window title="${c:l('app.title')}">
...
</window>
EL functions in this TLD file are described in the following subsections.