f:Extension
value[x]: minimum cardinality of 'value[x]' is 1
f:Extension/f:value[x] 1
value: minimum cardinality of 'value' is 1
comparator: maximum cardinality of 'comparator' is 0
unit: minimum cardinality of 'unit' is 1
system: maximum cardinality of 'system' is 0
code: maximum cardinality of 'code' is 0