A problem act (templateId 2.16.840.1.113883.10.20.1.27) SHALL be represented with Act. The value for "Act / classCode" in a problem act SHALL be "ACT" 2.16.840.1.113883.5.6 ActClass STATIC. The value for "Act / moodCode" in a problem act SHALL be "EVN" 2.16.840.1.113883.5.1001 ActMood STATIC. A problem act SHALL contain at least one Act / id. The value for "Act / code / @NullFlavor" in a problem act SHALL be "NA" "Not applicable" 2.16.840.1.113883.5.1008 NullFlavor STATIC. A problem act MAY contain exactly one Act / effectiveTime, to indicate the timing of the concern (e.g. the time the problem was noted). A problem act SHALL contain one or more Act / entryRelationship. A problem act MAY contain exactly one episode observation. The template identifier for an episode observation is 2.16.840.1.113883.10.20.1.41. A problem act MAY contain exactly one patient awareness. A problem act SHOULD include one or more problem observations (templateId 2.16.840.1.113883.10.20.1.28). The target of a problem act with Act / entryRelationship / @typeCode=”SUBJ” SHOULD be a problem observation (in the Problem section) or alert observation (in the Alert section, see section 3.9 Alerts), but MAY be some other clinical statement.