The contents of the html element are an XHTML fragment containing only the basic html formatting elements described in chapters 7-11 and 15 of the HTML 4.0 standard, 'anchor' elements (either name or href), images and internally contained stylesheets. The XHTML content SHALL NOT contain a head, a body, external stylesheet references, scripts, forms, base/link/xlink, frames, iframes and objects.

Multiple repetitions are available to support availability (one server might be down) as well as to accommodate the possibility that different servers might be needed for different value sets. In either case, client behavior is to try different servers from the available list until one is successful. There is no implication to the order in which the servers are listed. If no service is listed and terminology services are needed, the $expand operation should be invoked on the base URL for the payer.

If set to true, all systems that claim to support this extension and that render elements from the resource SHALL either render the content as required by the style extensions (style, xhtml and markdown or shall indicate to the user that the resource (or specific elements in the resource) cannot be appropriately rendered by the system.

Provide either unitOption(s) or unitValueSet. If either of the extensions are present, the units for a Quantity element are constrained to only the units listed by the extensions - i.e. it is treated as a "required", not an "extensible" binding. In the absence of either, any unit is valid. See additional guidance and examples in the SDC implementation guide. If this extension present and an answer is provided for the question item in the QuestionnaireResponse, then the valueQuantity SHALL have a Quantity.code and Quantity.system that match the Coding.code and system of one of the allowed values if the Coding has a code and/or system. If the Coding only has a display, then the Quantity.unit must match. (Note that Coding with only a display is strongly discouraged.) If there is a match on code and system, but no match on display/unit, systems MAY raise a warning. However, because of translation and bandwidth considerations, some systems MAY opt to drop the unit or express it in an alternate language. Validation of the Quantity unit MAY be performed by using the $validateCode operation, populating the elements passed into the operation from the Quantity.code, system and unit elements.

Sets minimum expectations for questionnaire support for SDC-conformant systems, regardless of which SDC capabilities they're making use of.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

The status of the narrative - whether it's entirely generated (from just the defined data or the extensions too), or whether a human authored it and it may contain additional data.

The status of a resource narrative.

The actual narrative content, a stripped down version of XHTML.

The contents of the html element are an XHTML fragment containing only the basic html formatting elements described in chapters 7-11 and 15 of the HTML 4.0 standard, 'anchor' elements (either name or href), images and internally contained stylesheets. The XHTML content SHALL NOT contain a head, a body, external stylesheet references, scripts, forms, base/link/xlink, frames, iframes and objects.

Information captured by the author/maintainer of the questionnaire for development purposes, not intended to be seen by users.

Allows capture of todos, rationale for design decisions, etc. It can also be used to capture comments about the completion of the form in general. Allows commentary to be captured during the process of answering a questionnaire (if not already supported by the form design) as well as after the form is completed. Comments are not part of the "data" of the form. If a form prompts for a comment, this should be captured in an answer, not in this element. Formal assessments of the QuestionnareResponse would use Observation.

Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the whole questionnaire or a particular group or question within the questionnaire (depending on where the extension appears). If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against the preferredTerminologyServer rather than the local repository.

Multiple repetitions are available to support availability (one server might be down) as well as to accommodate the possibility that different servers might be needed for different value sets. In either case, client behavior is to try different servers from the available list until one is successful. There is no implication to the order in which the servers are listed. If no service is listed and terminology services are needed, the $expand operation should be invoked on the base URL for the payer.

Indicates the types of resources that can record answers to a Questionnaire. Open Issue: Should this extension be moved to core?

If present, indicates that this questionnaire has expectations with respect to assembly. Specifically, indicates whether this form requires assembly (i.e. it can't be used directly without invoking the $assemble operation operation on it) and/or whether it is intended for use only as a 'child' in an assembly process. The assembly processs might mean filling in item metadata based on information looked up from item.definitions and/or retrieving sub-questionnaires pointed to by sub-questionnaire extensions.

SDC-conformant Questionnaires SHALL declare this extension if they require an assembly process prior to use. If not declared, then the Questionnaire is not necessarily safe for use as a child form and does not require assembly prior to use.

Indicates that the style extensions (style, markdown and xhtml) in this resource instance are essential to the interpretation of the instance and that systems that are not capable of rendering using those extensions should not be used to render the resource.

If set to true, all systems that claim to support this extension and that render elements from the resource SHALL either render the content as required by the style extensions (style, xhtml and markdown or shall indicate to the user that the resource (or specific elements in the resource) cannot be appropriately rendered by the system.

An Extension

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).

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.

The base URL for the server to which questionnaire response associated with this questionnaire should be submitted. If multiple repetitions are present, the completed form should be sent to all listed endpoints.

Indicates that the form has been designed with an expectation that it will be submitted to the specified URI. If multiple endpoints are specified, expectation is that answers are submitted to all endpoints.

If no end-point is specified, then the form is not exclusively designed to be submitted to a specific site. If and where the form needs to be submitted or how the form should be internally processed must be inferred from external context or system business rules.

Endpoints may have expectations around authorization, etc. Some of this may be learned by consulting the CapabilityStatement associated with the endpoint.

Indicates that a signature (of the specified type) is needed when completing the QuestionnaireResponse.

If this appears at the Questionnaire level, then the signature will be gathered for the entire form when it is marked complete. If it appears on a particular item, then it will be gathered on that question or group when it is filled in. (E.g. seeking the user's initials beside certain questions.)

The signature can be captured using the http://hl7.org/fhir/StructureDefinition/questionnaireresponse-signature extension. See additional guidance and examples in the SDC implementation guide.

Specifies a constraint that is enforced on instantiated (or target) resources. This extension can be applied to definitional resources (such as ActivityDefinition or Measure) and indicates that the constraint should be enforced on resources that are instantiated from the definition.

Can be used on any definitional artifact to define a constraint that is enforced in the context of an instantiated resource. The constraint expression will have access to %target and %definition variables, where target is the instantiated resource, and definition is the definition used to instantiate.

A reference to a Library containing the formal logic used by the artifact.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

An Extension

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).

Resources that provide context for form processing logic (pre-population, flow-control, drop-down selection, etc.) when creating/displaying/editing a QuestionnaireResponse.

3 of these launch contexts are aligned with the existing SMART on FHIR "launch" contexts.

Variable specifying a logic to generate a variable for use in subsequent logic. The name of the variable will be added to FHIRPath's context when processing descendants of the element that contains this extension as well as extensions within the same element.

Ordering of variable extension declarations is significant as variables declared in one repetition of this extension might be used in subsequent extension repetitions

For questionnaires, see additional guidance and examples in the SDC implementation guide.

Specifies a query or other expression that identifies the resource (or set of resources for a repeating item) that should be used to support the population of this Questionnaire or Questionnaire.item on initial population. When populating the questionnaire, it will set the specified variable name to that resource repetition for use in processing items within the group.

May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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 is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

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.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

An absolute URI that is used to identify this questionnaire when it is referenced in a specification, model, design or an instance; also called its canonical identifier. This SHOULD be globally unique and SHOULD be a literal address at which at which an authoritative instance of this questionnaire is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the questionnaire is stored on different servers.

The name of the referenced questionnaire can be conveyed using the http://hl7.org/fhir/StructureDefinition/display extension.

… This is the id that will be used to link a QuestionnaireResponse to the Questionnaire the response is for.

The identifier that is used to identify this version of the questionnaire when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the questionnaire author and is not expected to be globally unique. For example, it might be a timestamp (e.g. yyyymmdd) if a managed version is not available. There is also no expectation that versions can be placed in a lexicographical sequence.

There may be different questionnaire instances that have the same identifier but different versions. The version can be appended to the url in a reference to allow a reference to a particular business version of the questionnaire with the format [url]|[version].

A short, descriptive, user-friendly title for the questionnaire.

This name does not need to be machine-processing friendly and may contain punctuation, white-space, etc.

An Extension

Identifies how the specified element should be rendered when displayed.

This extension would be equivalent to setting the HTML "style" attribute on the root element for the element containing the extension.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

This is an equivalent of the string on which the extension is sent, but includes additional XHTML markup, such as bold, italics, styles, tables, etc. Existing restrictions on XHTML content apply. Note that using markdown allows for greater flexibility of display.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

The status of this questionnaire. Enables tracking the life-cycle of the content.

Allows filtering of questionnaires that are appropriate for use versus not.

The lifecycle status of an artifact.

The types of subjects that can be the subject of responses created for the questionnaire.

If none are specified, then the subject is unlimited.

One of the resource types defined as part of this version of FHIR.

A Questionnaire SHOULD specify the subject. However, it is optional to support legacy questionnaires.

The period during which the questionnaire content was or is planned to be in active use.

The effective period for a questionnaire determines when the content is applicable for usage and is independent of publication and review dates. For example, a measure intended to be used for the year 2016 might be published in 2015.

Allows establishing a transition before a resource comes into effect and also allows for a sunsetting process when new versions of the questionnaire are or are expected to be used instead.

A particular question, question grouping or display text that is part of the questionnaire.

The content of the questionnaire is constructed from an ordered, hierarchical collection of items.

Information captured by the author/maintainer of the questionnaire for development purposes, not intended to be seen by users.

Allows capture of todos, rationale for design decisions, etc. It can also be used to capture comments about specific groups or questions within it. Allows commentary to be captured during the process of answering a questionnaire (if not already supported by the form design) as well as after the form is completed. Comments are not part of the "data" of the form. If a form prompts for a comment, this should be captured in an answer, not in this element. Formal assessments of the QuestionnareResponse would use Observation.

Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the whole questionnaire or a particular group or question within the questionnaire (depending on where the extension appears). If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against the preferredTerminologyServer rather than the local repository.

This includes those referenced by answerValueSet as well as the unitValueSet extension.

Media to render/make available as an accompaniment to the question being asked

This extension is used when defining high-level questionnaires that will then be used as a basis for 'derived' Questionnaires that are further refined for use in specific organizations or contexts. If the extension is present and set to 'true', it means that this item should be considered to be 'optional' from an adaptation perspective and that the question can be removed (i.e. not displayed) in derived questionnaires without impacting the validity of the instrument. Alternatively, the element can be marked as 'hidden' and 'readOnly' and have a value or descendant item values declared using initialValue or initialExpression. If the element with 'optionalDisplay=true' is marked as 'required=true', then this second approach is the only means to exclude the element from display.

If a group or question that contains other groups or questions is marked as "optional", all of its contents are automatically also treated as optional.

The short text for the item.

This element is useful for an item that require a shorter text when rendered (e.g. when displaying the item on a mobile phone).

If true, indicates that the extended item should not be displayed to the user.

If an item is hidden, all descendant items are hidden as well. See additional guidance and examples in the SDC implementation guide.

The label text to display beside free-text and/or unrestricted type values for an 'open' choice element. E.g. 'Other, please specify', or 'Additional condition', or 'More reason(s)', etc.

The type of data entry control or structure that should be used to render the item.

Different controls may be appropriate for different item types. It is up to the system rendering a questionnaire as to what controls it will support and for which data types. See additional guidance and examples in the SDC implementation guide.

Identifies the desired orientation when rendering a list of choices (typically radio-box or check-box lists).

Systems may choose to wrap answers rather than attempting to display them all in one row or column. Language conventions may determine the order in which the choices are listed (left-to-right or right-to-left, etc.). See additional guidance and examples in the SDC implementation guide.

Describes the intended purpose of the rendered text. For example - instructions, guidance on access control, maintenance information, etc.

See additional guidance and examples in the SDC implementation guide.

A URL that resolves to additional supporting information or guidance related to the question. See additional guidance and examples in the SDC implementation guide.

Provides guidelines for rendering multi-column choices. I.e. when displaying a list of codes (for choice or open-choice items) or a list of resources (for reference items), this extension allows the drop-down to have multiple columns. For codes, the author can pick additional code system properties to display - such as alternate display names strength or form for drug codes, etc. For references, the author can choose particular columns from the resource (e.g. first name, last name, specialty, address).

Each repetition represents a column to display.

When used with an item control that causes the question to appear as a column in a table, indicates the width to give to the column for this question.

code missing = pixels; code = % = percentage.

For slider-based controls, indicates the step size to use when toggling the control up or down.

See additional guidance and examples in the SDC implementation guide.

Additional instructions for the user to guide their input (i.e. a human readable version of a regular expression like "nnn-nnn-nnn"). In most UIs this is the placeholder (or 'ghost') text placed directly inside the edit controls and that disappear when the control gets the focus.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

Indicates whether the child items of a group or question item is displayed in collapsible form.

Identifies that the specified element should only appear in certain "modes" of operation.

See additional guidance and examples in the SDC implementation guide.

Indicates that a signature (of the specified type) is needed when completing the QuestionnaireResponse.

If this appears at the Questionnaire level, then the signature will be gathered for the entire form when it is marked complete. If it appears on a particular item, then it will be gathered on that question or group when it is filled in. (E.g. seeking the user's initials beside certain questions.)

The signature can be captured using the http://hl7.org/fhir/StructureDefinition/questionnaireresponse-signature extension. See additional guidance and examples in the SDC implementation guide.

The minimum number of times the group must appear, or the minimum number of answers for a question - when greater than 1.

Default assumption for "required" elements is minOccurs=1. See additional guidance and examples in the SDC implementation guide.

The maximum number of times the group must appear, or the maximum number of answers for a question - when greater than 1 and not unlimited.

Only relevant if the element has repeats=true and there's a need to constrain the number of allowed repetitions. See additional guidance and examples in the SDC implementation guide.

The minimum number of characters that must be present in the simple data type to be considered a "valid" instance.

For base64binary, reflects the number of characters representing the encoded data, not the number of bytes of the binary data. For questionnaires, see additional guidance and examples in the SDC implementation guide.

A regular expression that defines the syntax for the data element to be considered valid.

The inclusive lower bound on the range of allowed values for the data element.

Data type specified must be the same as the data type for the data element. For questionnaires, see additional guidance and examples in the SDC implementation guide.

The inclusive upper bound on the range of allowed values for the data element.

Data type specified must be the same as the data type for the data element. For questionnaires, see additional guidance and examples in the SDC implementation guide.

The inclusive lower bound on the range of allowed values for a 'quantity' type question. Open Issue: Revisit whether this should be folded into the regular minValue extension once there are better capabilities around defining conformance expectations regarding extensions.

This must only be used if the set of permitted units is constrained to UCUM codes and the minimum checks will be performed by converting the answer.valueQuantity to the same units as the minQuantity unit prior to comparison.

The inclusive upper bound on the range of allowed values for a 'quantity' type question. Open Issue: Revisit whether this should be folded into the regular maxValue extension once there are better capabilities around defining conformance expectations regarding extensions.

This must only be used if the set of permitted units is constrained to UCUM codes and the maximum checks will be performed by converting the answer.valueQuantity to the same units as the maxQuantity unit prior to comparison.

Identifies the maximum number of decimal places that may be specified for the data element.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

Identifies the kind(s) of attachment allowed to be sent for an element.

This extension only has meaning if the element has a type of Attachment. For questionnaires, see additional guidance and examples in the SDC implementation guide.

For attachment answers, indicates the maximum size in bytes an attachment can be.

This extension only has meaning if the element has a type of Attachment. For questionnaires, see additional guidance and examples in the SDC implementation guide.

A complex expression that provides a list of the allowed options that should be enabled or disabled based on the evaluation of a provided expression. It allows toggling of allowed answers based on context, including the answers provided to other expressions.

For example, this allows a list of conditions to be modified based on the gender of the patient

A unit that the user may choose when providing a quantity value.

Provide either unitOption(s) or unitValueSet. If either of the extensions are present, the units for a Quantity element are constrained to only the units listed by the extensions - i.e. it is treated as a "required", not an "extensible" binding. In the absence of either, any unit is valid. See additional guidance and examples in the SDC implementation guide. If this extension present and an answer is provided for the question item in the QuestionnaireResponse, then the valueQuantity SHALL have a Quantity.code and Quantity.system that match the Coding.code and system of one of the allowed values if the Coding has a code and/or system. If the Coding only has a display, then the Quantity.unit must match. (Note that Coding with only a display is strongly discouraged.) If there is a match on code and system, but no match on display/unit, systems MAY raise a warning. However, because of translation and bandwidth considerations, some systems MAY opt to drop the unit or express it in an alternate language.

A set of units that the user may choose when providing a quantity value.

Provide either unitOption(s) or unitValueSet. If either of the extensions are present, the units for a Quantity element are constrained to only the units listed by the extensions - i.e. it is treated as a "required", not an "extensible" binding. In the absence of either, any unit is valid. See additional guidance and examples in the SDC implementation guide. If this extension present and an answer is provided for the question item in the QuestionnaireResponse, then the valueQuantity SHALL have a Quantity.code and Quantity.system that match the Coding.code and system of one of the allowed values if the Coding has a code and/or system. If the Coding only has a display, then the Quantity.unit must match. (Note that Coding with only a display is strongly discouraged.) If there is a match on code and system, but no match on display/unit, systems MAY raise a warning. However, because of translation and bandwidth considerations, some systems MAY opt to drop the unit or express it in an alternate language. Validation of the Quantity unit MAY be performed by using the $validateCode operation, populating the elements passed into the operation from the Quantity.code, system and unit elements.

Where the type for a question is "Reference", indicates a type of resource that is permitted.

This extension only has meaning if the question.type = Reference. If no allowedResource extensions are present, the presumption is that any type of resource is permitted. If multiple are present, then any of the specified types are permitted. See additional guidance and examples in the SDC implementation guide.

Where the type for a question is "Reference", indicates a profile that the resource instances pointed to in answers to this question must be valid against.

If multiple profiles are present, then the resource must be valid against at least one of them. See additional guidance and examples in the SDC implementation guide.

A FHIRPath or CQL expression, or FHIR Query that resolves to a list of candidate answers for the question item or that establishes context for a group item. The user may select from among the candidates to choose answers for the question.

The results of the expression must correspond to the item type of the question the element appears on or must correspond to a resource, backbone element or complex data type for a group item. Resources are considered a match for the Reference item type. Quantity can be a match for decimal and integer items so long as a questionnaire-unit extension is present.

For items of type reference, the reference can be populated either by picking an existing entity or by creating a new one. In the latter case, this Questionnaire allows specifying the Questionnaire to use in creating the target instance. Typically this will result in a QuestionnaireResponse that can be extracted to produce the desired resource. However, if the target resource for the reference is a QuestionnaireResponse, then the QuestionnaireResponse resulting from the Questionnaire can be referenced directly.

Specifies a constraint that is enforced on instantiated (or target) resources. This extension can be applied to definitional resources (such as ActivityDefinition or Measure) and indicates that the constraint should be enforced on resources that are instantiated from the definition.

Can be used on any definitional artifact to define a constraint that is enforced in the context of an instantiated resource. The constraint expression will have access to %target and %definition variables, where target is the instantiated resource, and definition is the definition used to instantiate.

Initial value for a question answer as determined by an evaluated expression.

Initial value is only calculated at the time the QuestionnaireResponse is first generated.

Calculated value for a question answer as determined by an evaluated expression.

Calculated value is updated as other answers in the QuestionnaireResponse are filled in.

An expression that returns a boolean value for whether to enable the item.

This is only permitted when the containing item does NOT have any enableWhen elements.

Provides a computable unit of measure associated with numeric questions to support subsequent computation on responses. This is for use on items of type integer and decimal, and it's purpose is to support converting the integer or decimal answer into a Quantity when extracting the data into a resource.

The human-readable unit is conveyed as a display element. This element is for computation purposes.

A FHIR Query that resolves to one or more resources that can be displayed to the user to help provide context for answering a question. For example, if the question is "Has the patient discussed this issue on any visits in the past year?", the contextExpression might return the set of patient's encounters for the prior 12 month period to help jog the practitioner's memory.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

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.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

An identifier that is unique within the Questionnaire allowing linkage to the equivalent item in a QuestionnaireResponse resource.

This ''can'' be a meaningful identifier (e.g. a LOINC code) but is not intended to have any meaning. GUIDs or sequential numbers are appropriate here.

QuestionnaireResponse does not require omitted items to be included and may have some items that repeat, so linkage based on position alone is not sufficient.

A short label for a particular group, question or set of display text within the questionnaire used for reference by the individual completing the questionnaire.

These are generally unique within a questionnaire, though this is not guaranteed. Some questionnaires may have multiple questions with the same label with logic to control which gets exposed. Typically, these won't be used for "display" items, though such use is not prohibited. Systems SHOULD NOT generate their own prefixes if prefixes are defined for any items within a Questionnaire.

Separating the label from the question text allows improved rendering. Also, instructions will often refer to specific prefixes, so there's a need for the questionnaire design to have control over what labels are used.

An Extension

Identifies how the specified element should be rendered when displayed.

This extension would be equivalent to setting the HTML "style" attribute on the root element for the element containing the extension.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

This is an equivalent of the string on which the extension is sent, but includes additional XHTML markup, such as bold, italics, styles, tables, etc. Existing restrictions on XHTML content apply. Note that using markdown allows for greater flexibility of display.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

The name of a section, the text of a question or text content for a display item.

When using this element to represent the name of a section, use group type item and also make sure to limit the text element to a short string suitable for display as a section heading. Group item instructions should be included as a display type item within the group.

An Extension

Identifies how the specified element should be rendered when displayed.

This extension would be equivalent to setting the HTML "style" attribute on the root element for the element containing the extension.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

This is an equivalent of the string on which the extension is sent, but includes additional XHTML markup, such as bold, italics, styles, tables, etc. Existing restrictions on XHTML content apply. Note that using markdown allows for greater flexibility of display.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

An expression that, when evaluated, provides the value for the element on which it appears.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

The type of questionnaire item this is - whether text for display, a grouping of other items or a particular type of data to be captured (string, integer, coded choice, etc.).

Time is handled using "string". File is handled using Attachment. (Content can be sent as a contained binary).

Distinguishes groups from questions and display text and indicates data type for questions.

Defines the format in which the user is to be prompted for the answer.

A constraint indicating that this item should only be enabled (displayed/allow answers to be captured) when the specified condition is true.

If multiple repetitions of this extension are present, the item should be enabled when the condition for any of the repetitions is true. I.e. treat "enableWhen"s as being joined by an "or" clause. This element is a modifier because if enableWhen is present for an item, "required" is ignored unless one of the enableWhen conditions is met. When an item is disabled, all of its descendants are disabled, regardless of what their own enableWhen logic might evaluate to.

Allows questionnaires to adapt based on answers to other questions. E.g. If physical gender is specified as a male, no need to capture pregnancy history. Also allows conditional display of instructions or groups of questions.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

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.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

The linkId for the question whose answer (or lack of answer) governs whether this item is enabled.

If multiple question occurrences are present for the same question (same linkId), then this refers to the nearest question occurrence reachable by tracing first the "ancestor" axis and then the "preceding" axis and then the "following" axis.

Specifies the criteria by which the question is enabled.

The criteria by which a question is enabled.

A value that the referenced question is tested using the specified operator in order for the item to be enabled.

Allowed values to answer questions.

Controls how multiple enableWhen values are interpreted - whether all or any must be true.

This element must be specified if more than one enableWhen value is provided.

Controls how multiple enableWhen values are interpreted - whether all or any must be true.

An indication, if true, that the item must be present in a "completed" QuestionnaireResponse. If false, the item may be skipped when answering the questionnaire.

Questionnaire.item.required only has meaning for elements that are conditionally enabled with enableWhen if the condition evaluates to true. If an item that contains other items is marked as required, that does not automatically make the contained elements required (though required groups must contain at least one child element). The value may come from the ElementDefinition referred to by .definition.

The actual value