> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-ct-practical-guides/snomed-ct-reference-set-guide/3-requirements-and-use-cases.md).
# Requirements and Use Cases
Reference sets are useful for a range of purposes, and different types of reference sets have been defined to meet various requirements. It is therefore important to understand the requirements for reference set usage in order to be able to select the appropriate reference set design.
Reference sets are useful for including, excluding and prioritizing content or managing the use of codes for data entry, communication or analysis purposes. Reference sets are important when customizing the use of SNOMED CT to meet specific requirements. For example, to meet national, jurisdictional or organizational requirements for recording clinical information, or to assess regional variations in disease prevalence or health delivery.
Practical use cases for SNOMED CT span the entire clinical information lifecycle from data entry, through to storage, display, communication, retrieval, analysis and reuse. Reference sets support effective and efficient use of SNOMED CT for a range of purposes at different stages in that lifecycle. For example, reference sets can assist with user interface customization, specification of reporting criteria, mapping to statistical classifications and representation of links to knowledge resources. They can also be used to represent terminology bindings and to validate the content of both inbound and outbound communications.
The subsequent sections will introduce some of the typical requirements and use cases for reference sets and the different types of reference sets which support these use cases.
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