A fixed quantity (no comparator)
Unique id for inter-element referencing
Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Additional content defined by implementations
May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Numerical value (with implicit precision)
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
< | <= | >= | > - how to understand the value
Not allowed to be used in this context
A human-readable form of the unit.
System that defines coded unit form
The identification of the system that provides the coded form of the unit.
Coded form of the unit
A computer processable form of the unit in some unit representation system.
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.