This element is used in the <composite:implementation> section. Any child components or template text within the composite component tag in the using page will be re-parented into the composite component at the point indicated by this tag's placement within the <composite:implementation> section. The normal use-case for this element is to have only one occurrence within the <composite:implementation> section. Inserting multiple occurrences may cause duplicate id errors. The results are undefined if there are multiple occurrences of this element in the <composite:implementation> section.