What is the preferred method to recognize the same content on different systems?

• A. By Business Identifiers
• B. By the resource URL
• C. By the file size
• D. By the date of creation

Answer: (A)

Using business identifiers is the preferred way to recognize the same content across different systems. In FHIR, a business identifier is an external, system-defined value that uniquely identifies a resource within a given domain. The identifier includes a system (the namespace) and a value, which makes it portable and stable across disparate systems, organizations, and servers. When multiple systems use the same identifier value within the same identifier system, they can reliably match records that refer to the same real-world item, even if internal IDs, URLs, or creation dates differ.

Relying on a resource URL isn’t ideal for cross-system matching because a URL is typically a server-local address and may change if the resource moves to another system. File size and creation date aren’t reliable identifiers either: they can vary with edits, processing, or imports and don’t uniquely pin a single real-world item across environments.

So, the stable cross-system key is the business identifier, expressed in FHIR as an Identifier with a defined system and value.