The "Negation in FHIR" and "Negation Rationale" sections suggest that the only valid way to determine if something was documented as not occuring is to look for a reason. This means that any event that was documented as not happening (e.g., an immunization not administered) but didn't document a reason would not be recognized as a negation. This seems wrong. If there is documentation that something didn't happen, then we know it didn't happen, whether or not there is a reason. Whether or not a reason is needed should be determined based on the specific context of the guideline, not based on a global requirement from the CPG IG.