From Joomla! Documentation
The "API15" namespace is an archived namespace. This page contains information for a Joomla! version which is no longer supported. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.
JDocumentRendererHead is responsible for rendering the output for the <head> section of an HTML document. It is called whenever a
<jdoc:include type="head" /> statement is encountered in the document template.
Note that any internal stylesheet rules that may have been added by the JDocument/addStyleDeclaration method will be output after all the external stylesheet links (both the default ones and any that may have been added by calls to the JDocument/addStyleSheet method. This ensures that the correct stylesheet cascade is preserved.
|render||Renders the document head and returns the results as a string|
|fetchHead||Generates the head html and return the results as a string|
jimport( 'joomla.document.html.renderer.head' );