A search parameter that defines a named search item that can be used to search/filter on a resource.

In FHIR, search is not performed directly on a resource (by XML or JSON path), but on a named parameter that maps into the resource content.

An absolute URL that is used to identify this search parameter when it is referenced in a specification, model, design or an instance. This SHALL be a URL, SHOULD be globally unique, and SHOULD be an address at which this search parameter is (or will be) published.

To allow referencing and reusing search parameter definitions under other names on operational systems (in case of name clash).

A free text natural language name identifying the search parameter.

This is often the same as the code for the parameter, but does not need to be.

The status of this search parameter definition.

This is not intended for use with actual conformance statements, but where conformance statements are used to describe possible or desired systems.

A flag to indicate that this search parameter definition is authored for testing purposes (or education/evaluation/marketing), and is not intended to be used for genuine usage.

Allows filtering of search parameter definitions that are appropriate for use vs. not.

The name of the individual or organization that published the search parameter.

Helps establish the "authority/credibility" of the search parameter. May also allow for contact.

Usually an organization, but may be an individual. This item SHOULD be populated unless the information is available from context.

Contacts to assist a user in finding and communicating with the publisher.

May be a web site, an email address, a telephone number (tel:), etc.

The name of an individual to contact regarding the search parameter.

If there is no named individual, the telecom is for the organization as a whole.

Contact details for individual (if a name was provided) or the publisher.

The date (and optionally time) when the search parameter definition was published. The date must change when the business version changes, if it does, and it must change if the status code changes. In addition, it should change when the substantive content of the search parameter changes.

Additional specific dates may be added as extensions.

The Scope and Usage that this search parameter was created to meet.

The code used in the URL or the parameter name in a parameters resource for this search parameter.

For maximum compatibility, use only lowercase ASCII characters.

The base resource type that this search parameter refers to.

The type of value a search parameter refers to, and how the content is interpreted.

A description of the search parameters and how it used.

An XPath expression that returns a set of elements for the search parameter.

Note that the elements returned by the XPath are sometimes complex elements where logic is required to determine quite how to handle them; e.g. CodeableConcepts may contain text and/or multiple codings, where the codings themselves contain a code and a system.

How the search parameter relates to the set of elements returned by evaluating the xpath query.

Types of resource (if a resource is referenced).