This clinical trial opt-in example, in contrast to the first example in this section ("Chief Red Cloud") contains no element. The reason for this difference is not explained, so I am unsure whether it is significant or not: can an extension defining complex content have text for each of its fields? Also, "Chief Red Cloud" in the first example is confusing because it is outside the definition, and perhaps it has nothing at all to do with extensions? Clarified. svn revision 4601 2015/03/19 MnM/FHIR Block Vote: Austin/Gordy 5-0-0