Constrains the Library's Type to asset-collection.

• pattern @ code

The US Public Health use context of the Library.

The US Public Health use context of the Library.

• profile @ resource.resolve()

Reference to a US Public Health Computable Library

The type of relationship to the related artifact. Fixed to composed-of.

Reference to a US Public Health Triggering ValueSet Library

The type of relationship to the related artifact. Fixed to composed-of.

The Library resource is a general-purpose container for knowledge asset definitions. It can be used to describe and expose existing knowledge assets such as logic libraries and information model descriptions, as well as to describe a collection of knowledge assets.

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.

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.

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 library 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 library is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the library is stored on different servers.

Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred. Multiple instances may share the same URL if they have a distinct version.

The determination of when to create a new version of a resource (same url, new version) vs. defining a new artifact is up to the author. Considerations for making this decision are found in Technical and Business Versions.

In some cases, the resource can no longer be found at the stated url, but the url itself cannot change. Implementations can use the meta.source element to indicate where the current master source of the resource can be found.

Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred. Multiple instances may share the same URL if they have a distinct version.

The determination of when to create a new version of a resource (same url, new version) vs. defining a new artifact is up to the author. Considerations for making this decision are found in Technical and Business Versions.

In some cases, the resource can no longer be found at the stated url, but the url itself cannot change. Implementations can use the meta.source element to indicate where the current master source of the resource can be found.

Allows the library to be referenced by a single globally unique identifier.

A formal identifier that is used to identify this library when it is represented in other formats, or referenced in a specification, model, design or an instance. e.g. CMS or NQF identifiers for a measure artifact. Note that at least one identifier is required for non-experimental active artifacts.

Typically, this is used for identifiers that can go in an HL7 V3 II (instance identifier) data type, and can then identify this library outside of FHIR, where it is not possible to use the logical URI.

Allows externally provided and/or usable business identifiers to be easily associated with the module.

The identifier that is used to identify this version of the library when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the library 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. To provide a version consistent with the Decision Support Service specification, use the format Major.Minor.Revision (e.g. 1.0.0). For more information on versioning knowledge assets, refer to the Decision Support Service specification. Note that a version is required for non-experimental active artifacts.

There may be different library 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 library with the format [url]|[version].

A natural language name identifying the library. This name should be usable as an identifier for the module by machine processing applications such as code generation.

The name is not expected to be globally unique. The name should be a simple alphanumeric type name to ensure that it is machine-processing friendly.

Support human navigation and code generation.

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

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

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

Allows filtering of libraries that are appropriate for use vs. not.

The lifecycle status of an artifact.

A Boolean value to indicate that this library is authored for testing purposes (or education/evaluation/marketing) and is not intended to be used for genuine usage.

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

Enables experimental content to be developed following the same lifecycle that would be used for a production-level library.

Constrains the Library's Type to asset-collection.

Identifies the type of library such as a Logic Library, Model Definition, Asset Collection, or Module Definition.

The type of knowledge asset this library contains.

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

Note that this is not the same as the resource last-modified-date, since the resource may be a secondary representation of the library. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

The name of the organization or individual that published the library.

Usually an organization but may be an individual. The publisher (or steward) of the library is the organization or individual primarily responsible for the maintenance and upkeep of the library. This is not necessarily the same individual or organization that developed and initially authored the content. The publisher is the primary point of contact for questions or issues with the library. This item SHOULD be populated unless the information is available from context.

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

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

May be a web site, an email address, a telephone number, etc.

A free text natural language description of the library from a consumer's perspective.

This description can be used to capture details such as why the library was built, comments about misuse, instructions for clinical use and interpretation, literature references, examples from the paper world, etc. It is not a rendering of the library as conveyed in the 'text' field of the resource itself. This item SHOULD be populated unless the information is available from context (e.g. the language of the library is presumed to be the predominant language in the place the library was created).

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate library instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

Assist in searching for appropriate content.

• pattern @ code

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate library instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

Assist in searching for appropriate content.

A code that identifies the type of context being specified by this usage context.

A code that specifies a type of context being specified by a usage context.

The US Public Health use context of the Library.

A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

A code that defines the specific value for the context being specified.

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate library instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

Assist in searching for appropriate content.

A code that identifies the type of context being specified by this usage context.

A code that specifies a type of context being specified by a usage context.

The US Public Health use context of the Library.

A value that defines the context specified in this context of use. The interpretation of the value is defined by the code.

A code that defines the specific value for the context being specified.

A legal or geographic region in which the library is intended to be used.

It may be possible for the library to be used in jurisdictions other than those for which it was originally designed or intended.

Countries and regions within which this artifact is targeted for use.

Related artifacts such as additional documentation, justification, or bibliographic references.

Each related artifact is either an attachment, or a reference to another resource, but not both.

Libraries must be able to provide enough information for consumers of the content (and/or interventions or results produced by the content) to be able to determine and understand the justification for and evidence in support of the content.

• profile @ resource.resolve()

Reference to a US Public Health Computable Library

Related artifacts such as additional documentation, justification, or bibliographic references.

Each related artifact is either an attachment, or a reference to another resource, but not both.

Libraries must be able to provide enough information for consumers of the content (and/or interventions or results produced by the content) to be able to determine and understand the justification for and evidence in support of the content.

The type of relationship to the related artifact. Fixed to composed-of.

The type of relationship to the related artifact.

The type of relationship to the related artifact.

The related resource, such as a library, value set, profile, or other knowledge resource.

If the type is predecessor, this is a reference to the succeeding knowledge resource. If the type is successor, this is a reference to the prior knowledge resource.

Reference to a US Public Health Triggering ValueSet Library

Related artifacts such as additional documentation, justification, or bibliographic references.

Each related artifact is either an attachment, or a reference to another resource, but not both.

Libraries must be able to provide enough information for consumers of the content (and/or interventions or results produced by the content) to be able to determine and understand the justification for and evidence in support of the content.

The type of relationship to the related artifact. Fixed to composed-of.

The type of relationship to the related artifact.

The type of relationship to the related artifact.

The related resource, such as a library, value set, profile, or other knowledge resource.

If the type is predecessor, this is a reference to the succeeding knowledge resource. If the type is successor, this is a reference to the prior knowledge resource.

The Library resource is a general-purpose container for knowledge asset definitions. It can be used to describe and expose existing knowledge assets such as logic libraries and information model descriptions, as well as to describe a collection of knowledge assets.

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

The only time that a resource does not have an id is when it is being submitted to the server using a create operation.

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

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.

The base language in which the resource is written.

Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

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.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope.

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags In their meta elements, but SHALL NOT have security labels.

May be used to represent additional information that is not part of the basic definition of the resource. 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.

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.

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 library 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 library is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the library is stored on different servers.

Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred. Multiple instances may share the same URL if they have a distinct version.

Allows the library to be referenced by a single globally unique identifier.

A formal identifier that is used to identify this library when it is represented in other formats, or referenced in a specification, model, design or an instance. e.g. CMS or NQF identifiers for a measure artifact. Note that at least one identifier is required for non-experimental active artifacts.

Typically, this is used for identifiers that can go in an HL7 V3 II (instance identifier) data type, and can then identify this library outside of FHIR, where it is not possible to use the logical URI.

Allows externally provided and/or usable business identifiers to be easily associated with the module.

The identifier that is used to identify this version of the library when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the library 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. To provide a version consistent with the Decision Support Service specification, use the format Major.Minor.Revision (e.g. 1.0.0). For more information on versioning knowledge assets, refer to the Decision Support Service specification. Note that a version is required for non-experimental active artifacts.

There may be different library 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 library with the format [url]|[version].

A natural language name identifying the library. This name should be usable as an identifier for the module by machine processing applications such as code generation.

The name is not expected to be globally unique. The name should be a simple alphanumeric type name to ensure that it is machine-processing friendly.

Support human navigation and code generation.

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

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

An explanatory or alternate title for the library giving additional information about its content.

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

Allows filtering of libraries that are appropriate for use vs. not.

A Boolean value to indicate that this library is authored for testing purposes (or education/evaluation/marketing) and is not intended to be used for genuine usage.

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

Enables experimental content to be developed following the same lifecycle that would be used for a production-level library.

Constrains the Library's Type to asset-collection.

A code or group definition that describes the intended subject of the contents of the library.

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

Note that this is not the same as the resource last-modified-date, since the resource may be a secondary representation of the library. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

The name of the organization or individual that published the library.

Usually an organization but may be an individual. The publisher (or steward) of the library is the organization or individual primarily responsible for the maintenance and upkeep of the library. This is not necessarily the same individual or organization that developed and initially authored the content. The publisher is the primary point of contact for questions or issues with the library. This item SHOULD be populated unless the information is available from context.

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

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

May be a web site, an email address, a telephone number, etc.

A free text natural language description of the library from a consumer's perspective.

This description can be used to capture details such as why the library was built, comments about misuse, instructions for clinical use and interpretation, literature references, examples from the paper world, etc. It is not a rendering of the library as conveyed in the 'text' field of the resource itself. This item SHOULD be populated unless the information is available from context (e.g. the language of the library is presumed to be the predominant language in the place the library was created).

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate library instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

Assist in searching for appropriate content.

• pattern @ code

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate library instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

Assist in searching for appropriate content.

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

A code that identifies the type of context being specified by this usage context.

The US Public Health use context of the Library.

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate library instances.

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

Assist in searching for appropriate content.

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

A code that identifies the type of context being specified by this usage context.

The US Public Health use context of the Library.

A legal or geographic region in which the library is intended to be used.

It may be possible for the library to be used in jurisdictions other than those for which it was originally designed or intended.

Explanation of why this library is needed and why it has been designed as it has.

This element does not describe the usage of the library. Instead, it provides traceability of ''why'' the resource is either needed or ''why'' it is defined as it is. This may be used to point to source materials or specifications that drove the structure of this library.

A detailed description of how the library is used from a clinical perspective.

A copyright statement relating to the library and/or its contents. Copyright statements are generally legal restrictions on the use and publishing of the library.

Consumers must be able to determine any legal restrictions on the use of the library and/or its content.

The date on which the resource content was approved by the publisher. Approval happens once when the content is officially approved for usage.

The 'date' element may be more recent than the approval date because of minor changes or editorial corrections.

The date on which the resource content was last reviewed. Review happens periodically after approval but does not change the original approval date.

If specified, this date follows the original approval date.

Gives a sense of how "current" the content is. Resources that have not been reviewed in a long time may have a risk of being less appropriate/relevant.

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

The effective period for a library 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 library are or are expected to be used instead.

Descriptive topics related to the content of the library. Topics provide a high-level categorization of the library that can be useful for filtering and searching.

Repositories must be able to determine how to categorize the library so that it can be found by topical searches.

An individiual or organization primarily involved in the creation and maintenance of the content.

An individual or organization primarily responsible for internal coherence of the content.

An individual or organization primarily responsible for review of some aspect of the content.

An individual or organization responsible for officially endorsing the content for use in some setting.

Related artifacts such as additional documentation, justification, or bibliographic references.

Each related artifact is either an attachment, or a reference to another resource, but not both.

Libraries must be able to provide enough information for consumers of the content (and/or interventions or results produced by the content) to be able to determine and understand the justification for and evidence in support of the content.

• profile @ resource.resolve()

Reference to a US Public Health Computable Library

Each related artifact is either an attachment, or a reference to another resource, but not both.

Libraries must be able to provide enough information for consumers of the content (and/or interventions or results produced by the content) to be able to determine and understand the justification for and evidence in support of the content.

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

The type of relationship to the related artifact. Fixed to composed-of.

A short label that can be used to reference the citation from elsewhere in the containing artifact, such as a footnote index.

A brief description of the document or knowledge resource being referenced, suitable for display to a consumer.

A bibliographic citation for the related artifact. This text SHOULD be formatted according to an accepted citation format.

Additional structured information about citations should be captured as extensions.

A url for the artifact that can be followed to access the actual content.

If a document or resource element is present, this element SHALL NOT be provided (use the url or reference in the Attachment or resource reference).

The document being referenced, represented as an attachment. This is exclusive with the resource element.

The related resource, such as a library, value set, profile, or other knowledge resource.

If the type is predecessor, this is a reference to the succeeding knowledge resource. If the type is successor, this is a reference to the prior knowledge resource.

Reference to a US Public Health Triggering ValueSet Library

Each related artifact is either an attachment, or a reference to another resource, but not both.

Libraries must be able to provide enough information for consumers of the content (and/or interventions or results produced by the content) to be able to determine and understand the justification for and evidence in support of the content.

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

The type of relationship to the related artifact. Fixed to composed-of.

A short label that can be used to reference the citation from elsewhere in the containing artifact, such as a footnote index.

A brief description of the document or knowledge resource being referenced, suitable for display to a consumer.

A bibliographic citation for the related artifact. This text SHOULD be formatted according to an accepted citation format.

Additional structured information about citations should be captured as extensions.

A url for the artifact that can be followed to access the actual content.

If a document or resource element is present, this element SHALL NOT be provided (use the url or reference in the Attachment or resource reference).

The document being referenced, represented as an attachment. This is exclusive with the resource element.

The related resource, such as a library, value set, profile, or other knowledge resource.

If the type is predecessor, this is a reference to the succeeding knowledge resource. If the type is successor, this is a reference to the prior knowledge resource.

The parameter element defines parameters used by the library.

Describes a set of data that must be provided in order to be able to successfully perform the computations defined by the library.

The content of the library as an Attachment. The content may be a reference to a url, or may be directly embedded as a base-64 string. Either way, the contentType of the attachment determines how to interpret the content.