String operationName = paramName.substring(0, paramName.indexOf('.'));
String parameterName = paramName.substring(paramName.indexOf('.')+1);
CatalogService cs = checkOperation(operationName);
values = cs.retrieveValues(parameterName);
// values null mean that the catalog was unable to determine
// anything about the specified parameter
if (values != null)
domainValues.addContent(values);