Indicates how questions within the questionnaire should be presented to the end-user. Specifically, differentiates whether the questions should be displayed one-at-a-time with no ability to adjust prior entries; one-at-a-time or continuously expanding where all questions up to the current question can be looked at and edited, or random, where all questions can be seen and the questions can be filled out in any order desired.

The prior-edit functionality can be accomplished by adding questions to the screen as each subsequent question is answered (resulting in all questions being displayed in a single screen) or with a view that shows only one question at a time but allows backward navigation to view and/or edit prior answers.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

• value @ url

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).