The accompanying mnemonic of an observation within a report ingested from Health Report Manager,
preserved exactly as the source message carried it.
This is the one of the three with nowhere else to go. The mnemonic reaches code.text only in
the narrow case where the message carried no accompanying description; otherwise this extension is
the only place it survives the conversion.
Present only when the source field was populated, and copied without normalisation, trimming or
validation. It is a source-local abbreviation, not a code from any published terminology: do not
match it against one.
Nexus EMR writes this today at
http://services.well.com/fhir/observation/hrm-accompanying-mnemonic (FHIR-372): it is live in
stored Observation.extension entries and in code, and is under migration to the canonical
declared here. Write the canonical; expect both until the migration completes.
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.
Comments
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.
Source of the definition for the extension code - a logical name or a URL.
Comments
The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.