metal:define-macro syntax:
argument ::= Name
The metal:define-macro statement defines a macro. The macro is
named by the statement expression, and is defined as the element
and its sub-tree.
In Zope, a macro definition is available as a sub-object of a
template's macros object. For example, to access a macro named
header in a template named master.html, you could use the path
expression master.html/macros/header.
Simple macro definition:
<p metal:define-macro="copyright">
Copyright 2001, <em>Foobar</em> Inc.
</p>