f:Observation subject: minimum cardinality of 'subject' is 1 f:Observation/f:value[x] 1 coding: minimum cardinality of 'coding' is 1 value: minimum cardinality of 'value' is 1 f:Observation/f:value[x]/f:coding 1 system: minimum cardinality of 'system' is 1 code: minimum cardinality of 'code' is 1