Requirements-Context Binding

Context binding is based on the concept of Concept Domains and Binding Realms. Initial model designs reference abstract concept domains that avoid referencing particular sets of codes. Specific sets of codes are then chosen within the context of a particular binding realm. For example, the set of codes used for diagnosis in the U.S. for human patients might be different than that chosen for veterinary patients in Canada.

MIF Reference: mif-model-vocabulary.xsd/ContextBinding

Requirement	HL7 Standards must be able to be constructed with coded elements that are not constrained to a specific set of codes, while still constraining the 'types' of codes that are considered appropriate and ensuring that consistent codes are used for a given concept across parts of a specification.
Rationale	There are variations in healthcare across countries, cultures, medical discipline (e.g. internal medicine vs. psychiatry), type of patient (e.g. human vs. veterinary or pediatric vs. geriatric) There is still a need to provide guidance about what types of codes are appropriate for a given element Failure to use consistent codes within different parts of a specification (e.g. one set of codes for create messages and a different set for update messages) would lead to interoperability issues
Methodology	Concept Domains

Requirement	It must be possible to take a given abstract Concept Domain definition and identify the specific set of codes (Value Set) that can be used in a given context
Rationale	This is a definition of what the Context Binding methodology is.
MIF	mif-model-vocabulary.xsd/ContextBinding/@conceptDomain mif-model-vocabulary.xsd/ContextBinding/@bindingRealmName mif-model-vocabulary.xsd/ContextBinding/@valueSet

Requirement	When defining a set of codes allowed to be used in a particular standard, there is a need to know what the "expectations" are for support or use of those codes is for implementers to be considered compliant with that standard
Rationale	Sometimes when codes are referenced in a specification, they're intended as "available" codes that define the set of codes that are allowed to be used without necessarily expecting a every application to support all of those codes Sometimes when codes are referenced in a specification, they're intended to say "Don't die/choke/raise an error if you receive one of these codes" Sometimes when codes are referenced in a specification, they're intended to say "You MUST support this code" - i.e. you must be able to capture, display, process, understand, etc. this code.
Methodology	Value Set Conformance

Requirement	When defining a set of codes for use in a specification, there's a need to differentiate whether the set of codes is considered exhaustive (i.e. all codes must come from the specified value set) or as the base preferred set that must be used if an appropriate code is available.
Rationale	Not all code systems or sets of code systems will necessarily fully encompass a domain space New concepts can arise that need to be communicated before a code is available in a standardized code system
Methodology	Coding Strength

Requirement	Context Bindings may change over time
Rationale	New terminologies are constantly in development. A terminology selected for a given use today may not be considered appropriate 3 years from now. For example, migrating from an ICD10 set of codes to a SNOMED CT set of codes when the jurisdiction is ready for the migration.
Methodology	Each vocabulary binding has a start date and may have an end date. (Bindings should not change frequently enough to necessitate a time component)
MIF	mif-model-vocabulary.xsd/ContextBinding/@effectiveDate mif-model-vocabulary.xsd/ContextBinding/@expiryDate

Requirement	Multiple independent sets of codes may be simultaneously considered 'valid' for a single concept domain within a specified context. Supplemental Requirement The set of codes used to cover a concept space by a given implementation must not have more than one concept drawn from more than one code system to represent a given concept Rationale With the exception of synonyms defined within a single code system, no code from two independent code system has exactly the same meaning Multiple codes with similar but not exactly equivalent meaning cause issues for mapping and equivalence testing
Rationale	In some cases, it will not be possible for a particular jurisdiction to 'land' on a single set of codes for political reasons. (E.g. a recognized need to use SNOMED CT but a large legacy base of ICD10) When transitioning from one agreed set of codes to a new set of codes, there may be a period of time where both sets of codes are considered acceptable
MIF	mif-model-vocabulary.xsd/ContextBinding/@bindingPriority