Applies to: the Golden Record strategies (MDM in EID mode and Probabilistic MDM) — strategies that resolve duplicates before storage do not create links.

Every MDM link has a match result that describes the relationship between the two resources it connects. Understanding these values is essential for interpreting link query results and knowing which administrative actions are available to you.

Values

Value	Meaning and Administrative Actions
`MATCH`	The source resource is linked to the Golden Resource. This is the normal, resolved state: the Golden Resource reflects the combined attributes of all source resources matched to it, according to the configured survivorship rules. Each source resource has at most one `MATCH` link. A `MATCH` link may have been created automatically by the system or confirmed manually by an administrator. Once manually assigned, it will not be changed automatically.
`POSSIBLE_MATCH`	The system found enough similarity between the source resource and the Golden Resource to flag the pair for review, but not enough to link them automatically. The source resource does not yet have a confirmed Golden Resource. This link requires your attention. You must either promote it to `MATCH` or dismiss it as `NO_MATCH` using `$mdm-update-link`. Until you act, the source resource remains unresolved.
`NO_MATCH`	You have confirmed that the source resource and the Golden Resource do not represent the same real-world entity. The system will not suggest this pair again. The source resource will be re-evaluated against other Golden Resources so that a correct link can be established. This result is always the outcome of a deliberate administrative action — the system never assigns it automatically.
`POSSIBLE_DUPLICATE`	The system has determined that two Golden Resources may represent the same real-world entity. Both endpoints of this link are Golden Resources — it does not connect a source resource to a Golden Resource. This link requires your attention. You have two options: Merge the two Golden Resources into one using `$mdm-merge-golden-resources`. Confirm they are distinct using `$mdm-not-duplicate`. The system will not flag this pair as a possible duplicate again.
`REDIRECT`	This link was created when two Golden Resources were merged via `$mdm-merge-golden-resources`. Both endpoints are Golden Resources. The deactivated Golden Resource points to the surviving active Golden Resource, and its status tag is set to `REDIRECTED`. The deactivated Golden Resource is read-only and cannot be modified through the FHIR endpoint. Source resources that were previously linked to it remain linked to it, and the system resolves them to the active Golden Resource through this redirect. No administrative action is required or available on a `REDIRECT` link.

Link Topology

NO_MATCH, POSSIBLE_MATCH, and MATCH always connect a source resource to a Golden Resource. POSSIBLE_DUPLICATE and REDIRECT always connect two Golden Resources to each other. Knowing which category a link falls into tells you what you will find at each endpoint when you query it.

MDM API Operations Reference MDM Virtualized Endpoint