In the API, where are "Included in Builds" and "Change Sets"?

As you can see from the "chain" overly on the icon, these are relationships. You will also notice you find them on the Links tab. These are not exposed as attributes.

See https://rsjazz.wordpress.com/2012/09/19/the-rtc-workitem-link-api-linking-workitems-to-other-elements/ and, very similar https://rsjazz.wordpress.com/2012/09/20/the-rtc-workitem-server-link-api-linking-to-work-items-and-other-elements/ and https://rsjazz.wordpress.com/2012/10/20/following-calm-links-using-the-java-client-or-server-api/ for more information about link API's.

They are exposed as references. There are different kinds of these references. Workitem references and URI references.

In
https://rsjazz.wordpress.com/2012/09/19/the-rtc-workitem-link-api-linking-workitems-to-other-elements/

you can find code how to analyze references and then follow the different ones

/**
 * Analyze a reference
 */
public void analyzeReference(IReference iReference) {
	if (iReference.isItemReference()) {
		Object resolvedRef = iReference.resolve();
		analyzeItem(resolvedRef);
	}
	if (iReference.isURIReference()){
		analyzeReferenceTarget(iReference);
	}
}

Hi Mike,

Have you tried using the plugin spy to find the api?  More details on the spy are available here: http://ryehle.wordpress.com/2011/11/21/finding-the-right-service-api-for-your-process-extension/.