http://hl7.org/fhir/us/core/StructureDefinition/head-occipital-frontal-circumference-percentile|8.0.0-ballot

The US Core Pediatric Head Occipital Frontal Circumference Percentile Profile inherits from the US Core Vital Signs Profile. This profile sets minimum expectations for the Observation resource to record, search, and fetch pediatric head occipital frontal circumference (OFC) percentile observations associated with a patient from birth to 37 Months of age using a standard LOINC code and UCUM units of measure. It specifies which *additional* core elements, extensions, vocabularies, and value sets **SHALL** be present in the resource and constrains how the elements are used. Providing the floor for standards development for specific use cases promotes interoperability and adoption.