Primitive type 'probability'
The probability assigned to the value, a decimal number between 0 (very uncertain) and 1 (certain).
A rational number with implicit precision
Do not use an IEEE type floating point type, instead use something that works like a true decimal, with inbuilt precision (e.g. Java BigInteger)
All FHIR elements must have a @value or children
hasValue() or (children().count() > id.count())
unique id for the element within a resource (for internal references)
Must have either extensions or value[x], not both