The text says: Each Immunization must have: ... a flag to indicate whether vaccine was given. Earlier versions of Immunization used a flag to convey that an immunization was not given, but in R4, this was incorporated into the status (as 'not-done'). As such, this requirement ("a flag to indicate whether vaccine was given") should be removed or reworded to indicate that not-given immunizations should be properly reported via the status attribute.