<jsp:doBody /> and <jsp:invoke /> can only be invoked from tag files, never ordinary JSPs. Their purpose is to evaluate the action's body or a fragment attribute respectively.
<jsp:body> on the other hand is used to provide a <jsp:element> with body content, which is a completely different issue. <jsp:body> may be used in either JSPs or tag files. [ June 26, 2006: Message edited by: Charles Lyons ]
Charles Lyons (SCJP 1.4, April 2003; SCJP 5, Dec 2006; SCWCD 1.4b, April 2004)
Author of OCEJWCD Study Companion for Oracle Exam 1Z0-899 (ISBN 0955160340 / AmazonAmazon UK )