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