File not found: http:/www.opensymphony.com/osworkflow/osworkflow.dtd

At this point, I'm merely trying to load the source into my IDE - the WSAD 5.0 ( WebSphere Application Developer ) - it's flagging a "file not found error" in the jira-workflow.xml. When I try to locate the missing DTD on the web, using Internet Explorer, at:

http://www.opensymphony.com/osworkflow/workflow.dtd

I browswer responds: "The page cannot be found"