(Quick Reference)
                layoutHead
Purpose
Used in layouts to render the contents of the head tag of the decorated page. Equivalent to the SiteMesh 
<decorator:head /> tag.
Examples
Example decorated page:
<html>
   <head>
        <meta name="layout" content="myLayout" />
        <script src="myscript.js" />
   </head>
   <body>Page to be decorated</body>
</html>Example decorator layout:
<html>
   <head>
        <script src="global.js" />
        <g:layoutHead />
   </head>
   <body><g:layoutBody /></body>
</html>Results in:
<html>
   <head>
        <script src="global.js" />
        <script src="myscript.js" />
   </head>
   <body>Page to be decorated</body>
</html>Source