f:Observation category: minimum cardinality of 'category' is 1 category: maximum cardinality of 'category' is 1 subject: minimum cardinality of 'subject' is 1 effective[x]: minimum cardinality of 'effective[x]' is 1 f:Observation/f:value[x] 1 value: minimum cardinality of 'value' is 1 unit: minimum cardinality of 'unit' is 1 system: minimum cardinality of 'system' is 1 code: minimum cardinality of 'code' is 1