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The GEDCOM X Conceptual Model

Status

This document specifies a conceptual model for exchanging genealogical data, and requests discussion and suggestions for improvements.

The current state of this document is as a "stable draft", and as such, the document may be subject to limited changes, BUT NOT backwards-incompatible changes, according to the discussion and suggestions for improvement.

Copyright Notice

Copyright 2011-2013 Intellectual Reserve, Inc.

License

This document is distributed under a Creative Commons Attribution-ShareAlike license. For details, see:

http://creativecommons.org/licenses/by-sa/3.0/

1. Introduction

The GEDCOM X Conceptual Model is a specification of formal concepts and types that are used to provide a standard model and vocabulary for describing genealogical data. Genealogical data is structured by data types such as persons, relationships, and sources.

1.1 Identifier, Version, and Dependencies

The identifier for this specification is:

http://gedcomx.org/conceptual-model/v1

For convenience, the GEDCOM X conceptual model may be referred to as "GEDCOM X Conceptual Model 1.0". This specification uses "GEDCOM X" or "GEDCOM X Conceptual Model" internally.

This specification is depends on the GEDCOM X Date Format specification identified by http://gedcomx.org/date/v1.

This specification refers to the GEDCOM X Event Types specification identified by http://gedcomx.org/event-types/v1 to recommend event types to be used.

This specification refers to the GEDCOM X Fact Types specification identified by http://gedcomx.org/fact-types/v1 to recommend fact types to be used.

This specification refers to the GEDCOM X Name Part Qualifiers specification identified by http://gedcomx.org/name-part-qualifiers/v1 to recommend name part qualifiers to be used.

1.2 Notational Conventions

1.2.1 Keywords

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC2119, as scoped to those conformance targets.

1.3 Definitions

1.3.1 Data Types and Properties

The term "data type" is used to refer to a formal description of a data structure. The term "property" is used to refer to a distinct component or element of a data type. For example, information about a person might be contained within a data structure that supplies the person's name, birth date, gender, etc. A "data type" defines the formal "properties" of a data structure.

When a property of a data type is specified as being of a particular data type, the value of the property inherits the corresponding requirements from that data type's definition. When a data type is specified as an "extension" of another data type, the extending data type inherits the corresponding requirements and properties from the extended data type's definition.

Data type definitions provided by this specification use the following elements:

  1. The identifier for the data type, which takes the form of a URI.
  2. The extension of the data type (if any) which specifies which data type is extended by the data type.
  3. The properties of the data type, which define the information the data type encapsulates.

1.3.2 Data Instances

The term "data instance" to refer to a particular instance, or instantiation, of a data type.

1.3.3 Basic Data Types

This section defines a set of basic data types that are used by GEDCOM X.

A "boolean" refers to the mathematical concept of binary-valued logic: true or false.

A "timestamp" refers to an instance of time, including values for year, month, date, hour, minute, second and timezone.

A "double" refers to an IEEE 754 binary64 value.

A "character" is an atomic unit of text as specified by ISO/IEC 10646.

A "string" is defined as a finite-length sequence of characters.

A "list" is defined as a sequence of data instances. When a property is defined in terms of a "list", the data type of the data instances in the list is also provided.

1.3.4 The URI Reference

The Uniform Resource Identifier ("URI") is fundamental to the GEDCOM X conceptual model. The URI is used to identify both the data types and data instances. The URI is also used to identify elements of the controlled vocabularies defined by GEDCOM X. The URI is specified by RFC 3986.

GEDCOM X resources use the URI to reference other entities. For example, a GEDCOM X Relationship identifies a person in the relationship by referencing a URI that identifies the person. When a property (such as the person1 property of Relationship) is of data type URI, the value of the property is interpreted as a "URI Reference" as defined by RFC 3986, section 4. This specification uses the term "URI" to refer to both a "URI" and a "URI Reference" as defined by RFC 3986.

1.3.5 Original and Normalized Values

When a property is identified as an "original value", the value of the property is interpreted as the literal value supplied by a user. If a property is identified as a "normalized value", the value of the property is assumed to be formally formatted (either by a user or by the application) for the purpose of easier processing, such as for display purposes.

1.3.6 Enumerated Values

Enumerated values are used throughout GEDCOM X to constrain values of properties to a limited (though not necessarily small) number of possibilities. Enumerated values are used to ensure portability and must be a discrete, machine-identifiable value based on a specific specification. Members of controlled vocabularies are enumerated values.

Enumerated values take the form of a URI. The base URI for enumerated values defined by GEDCOM X is http://gedcomx.org/. As such, if an enumerated value is provided as a relative URI reference as defined by RFC 3986 Section 4.2, the base URI to be used for reference resolution as defined by RFC 3986 Section 5 is is http://gedcomx.org/.

Enumerated values which are neither defined directly from this specification nor indirectly referenced by this specification SHOULD be declared in a freely-distributable specification and MUST NOT use the value http://gedcomx.org/ as a base URI.

1.3.7 Controlled Vocabularies

GEDCOM X defines a set of controlled vocabularies for the purposes of identifying the semantic context of data instances. A controlled vocabulary is often defined to create a set of "known types" of data instances such as facts, names, genders, etc. For example, a controlled vocabulary is specified to identify the set of known types of events so applications can share semantic context of the event.

Elements of a controlled vocabulary are identified by an enumerated value.

1.3.8 Text Types

In some cases, a text value must include styling or layout to fully convey its intended meaning. Where such a requirement has been identified, implementers can designate that a text value may include such styling or layout by specifying an alternate text type. The following text types are supported:

plain

The "plain" text type identifies plain text. "plain" is the default text type for text without an explicitly specified type.

xhtml

The "xhtml" text type identifies XHTML text complying with the XHTML 1.0 W3C Recommendation. In order to maximize compatibility and minimize security risks, support for the following subset of modules (defined by XHTML Modularization 1.1 W3C Recommendation](http://www.w3.org/TR/xhtml-modularization/)) is REQUIRED:

Support for other XHTML modules is OPTIONAL. Parsers MAY ignore elements from optional modules.

1.4 Internationalization Considerations

GEDCOM X is be designed to accommodate users and software of different languages and cultures. Genealogical data often needs to be interpreted from the perspective of its cultural context.

To this end, a property named lang is supported on relevant GEDCOM X data types. The value of this property is the locale of the data being processed. The locale is used to identify the cultural context of the data. The values of the lang property are language identifiers as defined by IETF BCP 47, Tags for the Identification of Languages; in addition, the empty string may be specified to explicitly state a processor may process the data as if it were provided in the default locale of the processor.

The lang property is optional. When a value for the lang property is provided, it is presumed to apply to the data instance and to any data it contains. The value of the lang property overrides the value of the lang property on any containing data. When a value for the lang property is neither provided on a data instance nor on any containing data instances, a processor MAY process the data as if it were provided in the default locale of the processor.

For example, to determine the cultural context of a given name form, the value of the lang property on the name form is used. If the lang property is not provided on the name form, the value of the lang property on the name is used. If the lang property is not provided on the name, the value of the lang property on the person is used. If the lang property is not provided on the person, the value of the lang property on the containing dataset is used. If the lang property on the containing dataset is not provided, the default locale of the processor is used.

In order to prevent undue burden on producers and consumers of GEDCOM X data, not all data types provide multiple values for properties that are used for user input. For example, the text of a note is not defined as a list of language-identified strings. However, some cases have been identified where multi-valued input is needed for the benefit of exchanging genealogical data across cultural boundaries. Such cases include the need to input multiple name forms and the need to identify multiple titles for a source.

2. Top-Level Data Types

The data types in this section are designated as "top-level" data types because they define the top-level units of genealogical data. A GEDCOM X data set is defined as a collection of instances of top-level data types. The definitions of top-level data types stand separately from the definitions of other top-level data types and the lifecycle of instances of these data types is distinct from the lifecycle of instances of the other top-level data types.

2.1 The "Person" Data Type

The Person data type defines a description of a person.

identifier

The identifier for the Person data type is:

http://gedcomx.org/v1/Person

extension

This data type extends the following data type:

http://gedcomx.org/v1/Subject

properties

name description data type constraints
private Whether this instance of Person has been designated for limited distribution or display. boolean OPTIONAL. A description of how implementations should use private data is outside the scope of this specification.
gender The gender of the person. http://gedcomx.org/v1/Gender OPTIONAL.
names The names of the person. List of http://gedcomx.org/v1/Name. Order is preserved. OPTIONAL. If more than one name is provided, names are assumed to be given in order of preference, with the most preferred name in the first position in the list.
facts The facts of the person. List of http://gedcomx.org/v1/Fact. Order is preserved. OPTIONAL.

2.2 The "Relationship" Data Type

The Relationship data type describes a relationship between two persons.

identifier

The identifier for the Relationship data type is:

http://gedcomx.org/v1/Relationship

extension

This data type extends the following data type:

http://gedcomx.org/v1/Subject

properties

name description data type constraints
type Enumerated value identifying the type of the relationship. Enumerated Value OPTIONAL. If provided, MUST identify a relationship type, and use of a known relationship type is RECOMMENDED.
person1 Reference to the first person in the relationship. URI REQUIRED. MUST resolve to an instance of http://gedcomx.org/v1/Person
person2 Reference to the second person in the relationship. URI REQUIRED. MUST resolve to an instance of http://gedcomx.org/v1/Person
facts The facts about the relationship. List of http://gedcomx.org/v1/Fact. Order is preserved. OPTIONAL.

Note: when a relationship type implies direction, the relationship is said to be from person1 to person2. For example, in a parent-child relationship, the relationship is said to be "from a parent to a child"; therefore, the person1 property refers to the parent and the person2 property refers to the child.

2.2.1 Known Relationship Types

The following relationship types are defined by GEDCOM X:

URI description
http://gedcomx.org/Couple A relationship of a pair of persons.
http://gedcomx.org/ParentChild A relationship from a parent to a child.

2.3 The "SourceDescription" Data Type

The SourceDescription data type defines a description of a source of genealogical information.

identifier

The identifier for the "SourceDescription" data type is:

http://gedcomx.org/v1/SourceDescription

properties

name description data type constraints
id An identifier for the data structure holding the source description data. string OPTIONAL. The id is to be used as a "fragment identifier" as defined by RFC 3986, Section 3.5. As such, the constraints of the id are provided in the definition of the media type (e.g. XML, JSON) of the data structure.
resourceType Enumerated value identifying the type of resource being described. Enumerated Value OPTIONAL. If provided, MUST identify a resource type, and use of a known resource type is RECOMMENDED.
citations The citation(s) for this source. http://gedcomx.org/v1/SourceCitation. Order is preserved. REQUIRED. At least one citation MUST be provided. If more than one citation is provided, citations are assumed to be given in order of preference, with the most preferred citation in the first position in the list.
mediaType A hint about the media type of the resource being described. string OPTIONAL. If provided, MUST be a valid MIME (media) type as specified by RFC 4288.
about A uniform resource identifier (URI) for the resource being described. URI OPTIONAL.
mediator A reference to the entity that mediates access to the described source. URI OPTIONAL. If provided, MUST resolve to an instance of http://gedcomx.org/v1/Agent.
sources A list of references to any sources from which this source is derived. List of http://gedcomx.org/v1/SourceReference OPTIONAL.
analysis A reference to a document containing analysis about this source. URI OPTIONAL. If provided, MUST resolve to an instance of http://gedcomx.org/v1/Document of type http://gedcomx.org/Analysis.
componentOf A reference to the source that contains this source, i.e. its parent context. Used when the description of a source is not complete without the description of its parent (or containing) source. http://gedcomx.org/v1/SourceReference OPTIONAL.
titles The display name(s) for this source. List of http://gedcomx.org/TextValue. Order is preserved. OPTIONAL. If more than one title is provided, titles are assumed to be given in order of preference, with the most preferred title in the first position in the list.
notes A list of notes about a source. List of http://gedcomx.org/Note OPTIONAL.
attribution The attribution of this source description. http://gedcomx.org/Attribution OPTIONAL. If not provided, the attribution of the containing data set (e.g. file) of the source description is assumed.

2.3.1 Known Resource Types

The following resource types are identified by GEDCOM X:

URI description
http://gedcomx.org/Collection A collection of genealogical resources. A collection may contain physical artifacts (such as a collection of books in a library), records (such as the 1940 U.S. Census), or digital artifacts (such as an online genealogical application).
http://gedcomx.org/PhysicalArtifact A physical artifact, such as a book.
http://gedcomx.org/DigitalArtifact A digital artifact, such as a digital image of a birth certificate or other record.
http://gedcomx.org/Record A historical record, such as a census record or a vital record.

2.4 The "Agent" Data Type

The Agent data type defines someone or something that curates genealogical data, such as a genealogical researcher, user of software, or organization.

identifier

The identifier for the Agent data type is:

http://gedcomx.org/v1/Agent

properties

name description data type constraints
id An identifier for the data structure holding the agent data. string OPTIONAL. The id is to be used as a "fragment identifier" as defined by RFC 3986, Section 3.5. As such, the constraints of the id are provided in the definition of the media type (e.g. XML, JSON) of the data structure.
names The name(s) of the person or organization. List of http://gedcomx.org/TextValue. Order is preserved. OPTIONAL. If more than one name is provided, names are assumed to be given in order of preference, with the most preferred name in the first position in the list.
homepage The homepage of the person or organization. URI OPTIONAL.
openid The openid of the person or organization. URI OPTIONAL.
accounts The online account(s) of the person or organization. List of http://gedcomx.org/v1/OnlineAccount. Order is preserved. OPTIONAL.
emails The email address(es) of the person or organization. List of URI. Order is preserved. OPTIONAL. If provided, MUST resolve to a valid e-mail address (e.g. "mailto:someone@gedcomx.org").
phones The phone(s) (voice, fax, mobile) of the person or organization. List of URI. Order is preserved. OPTIONAL. If provided, MUST resolve to a valid phone number (e.g. "tel:+1-201-555-0123").
addresses The address(es) of the person or organization. List of http://gedcomx.org/v1/Address. Order is preserved. OPTIONAL.
person A reference to the person that describes this agent. URI OPTIONAL. MUST resolve to an instance of http://gedcomx.org/v1/Person.

2.5 The "Event" Data Type

The Event data type defines a description of a historical event.

identifier

The identifier for the Event data type is:

http://gedcomx.org/v1/Event

extension

This data type extends the following data type:

http://gedcomx.org/v1/Subject

properties

name description data type constraints
type Enumerated value identifying the type of the event. Enumerated Value OPTIONAL. If provided, MUST identify an event type, and use of a known event type is RECOMMENDED.
date The date of the event. http://gedcomx.org/v1/Date OPTIONAL.
place A reference to the place applicable to this event. http://gedcomx.org/v1/PlaceReference OPTIONAL.
roles Information about how persons participated in the event. List of http://gedcomx.org/v1/EventRole. Order is preserved. OPTIONAL.

2.5.1 Known Event Types

The following event types are defined by GEDCOM X:

URI description
http://gedcomx.org/Adoption An adoption event.
http://gedcomx.org/Birth A birth event.
http://gedcomx.org/Burial A burial event.
http://gedcomx.org/Census A census event.
http://gedcomx.org/Christening A christening event at birth. Note that this enumerated value does not identify an adult christening.
http://gedcomx.org/Death A death event.
http://gedcomx.org/Divorce A divorce event.
http://gedcomx.org/Marriage A marriage event.

In addition to these elements, processors SHOULD support any other elements defined by the GEDCOM X Event Types specification.

2.5.2 Events Versus Facts

GEDCOM X implementations need to be able to recognize the difference between the concept of an "event" and the concept of a "fact" as defined by this specification in order to correctly use the data types associated with these concepts. This section is provided for the purpose of explicitly defining and distinguishing the two concepts.

An "event" is an occurrence that happened at a specific time or period of time, often at a specific place or set of places. Genealogically relevant events are often described by referencing the persons that played a role in that event. Hence events often refer to persons and might infer relationships, but events are described independently of those persons and relationships.

A "fact" is a data item that is presumed to be true about a specific subject, such as a person or relationship. A time or place is often, but not always, applicable to a fact. Facts do not exist outside the scope of the subject to which they apply.

Events are often used to infer facts. A marriage event, for example, infers the fact that two persons were married, and birth event infers the fact that a person was born. Facts also sometimes infer events, but the existence of a fact might not always justify a description of an event. For example, a birth fact provided by a census record might not warrant a description of a birth event, even though the existence of such an event is implied. On the other hand, a birth record that provides information about biological parents, adoptive parents, additional witnesses, etc. might justify a description of the event in addition to descriptions of any facts provided by the record.

Despite the occasional inference of facts from events and vice versa, this specification dictates that the two concepts are described independently. This version of the specification does not provide a direct association between instances of the two data types, although an indirect association can be found via the event role.

2.6 The "Document" Data Type

The Document data type defines the base conceptual model for genealogical data that are managed as textual documents.

identifier

The identifier for the Document data type is:

http://gedcomx.org/v1/Document

extension

This data type extends the following data type:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
type Enumerated value identifying the type of the document. Enumerated Value OPTIONAL. If provided, MUST identify a document type, and use of a known document type is RECOMMENDED.
extracted Whether this document is to be constrained as an extracted conclusion. boolean OPTIONAL. Default: false. Refer to Extracted Conclusion Constraints.
textType The type of text in the text property. string OPTIONAL. If provided, the value MUST be a valid text type. If no value is provided, "plain" is assumed.
text The text of the document. string REQUIRED.
attribution The attribution of the document. http://gedcomx.org/Attribution OPTIONAL. If not provided, the attribution of the containing data set (e.g. file) of the document is assumed.

2.6.1 Known Document Types

The following document types are defined by GEDCOM X:

URI description
http://gedcomx.org/Abstract The document is an abstract of a record or document.
http://gedcomx.org/Transcription The document is a transcription of a record or document.
http://gedcomx.org/Translation The document is a translation of a record or document.
http://gedcomx.org/Analysis The document is an analysis done by a researcher; a genealogical proof statement is an example of one kind of analysis document.

2.7 The "PlaceDescription" Data Type

The PlaceDescription data type describes the details of a place in terms of its name and possibly its type, time period, and/or a geospatial description -- functioning as a description of a place as a snapshot in time.

identifier

The identifier for the PlaceDescription data type is:

http://gedcomx.org/v1/PlaceDescription

extension

This data type extends the following data type:

http://gedcomx.org/v1/Subject

properties

name description data type constraints
names A list of standardized (or normalized), fully-qualified (in terms of what is known of the applicable jurisdictional hierarchy) names for this place that are applicable to this description of this place. List of http://gedcomx.org/v1/TextValue. Order is preserved. REQUIRED. The list MUST contain at least one name.
type An implementation-specific uniform resource identifier (URI) used to identify the type of a place (e.g., address, city, county, province, state, country, etc.). Enumerated Value OPTIONAL. There is no current definition of a set of known place types.
place An identifier for the place being described. URI OPTIONAL. Descriptions that provide the same value for place are interpreted as alternate descriptions of the same place. If provided, MUST NOT use a base URI of http://gedcomx.org/. If provided, the value MAY resolve to an external resource that is application-specific and outside the scope of this specification.
latitude Angular distance, in degrees, north or south of the Equator (0.0 degrees). double OPTIONAL. If provided, MUST provide longitude also. Values range from −90.0 degrees (south of the equator) to 90.0 degrees (north of the equator). It is assumed that descriptions that provide the same value for the place property share identical longitude values.
longitude Angular distance, in degrees, east or west of the Prime Meridian (0.0 degrees). double OPTIONAL. If provided, MUST provide latitude also. Values range from −180.0 degrees (west of the Meridian) to 180.0 degrees (east of the Meridian). It is assumed that descriptions that provide the same value for the place property share identical latitude values.
temporalDescription A description of the time period to which this place description is relevant. http://gedcomx.org/v1/Date OPTIONAL.
spatialDescription A reference to a geospatial description of this place. URI OPTIONAL. It is RECOMMENDED that this geospatial description resolve to a KML document.

3. Component-Level Data Types

The data types in this section are designated as "component-level" data types because they are designed to be referenced and re-used by other data types, most notably the top-level data types. The lifecycle of instances of these data types is generally tied to the lifecycle of instances of a top-level data type.

3.1 The "Identifier" Data Type

The Identifier data type defines the data structure used to supply an identifier of a genealogical resource.

The Identifier data type does NOT support extension properties (see Extension Properties).

identifier

The identifier for the "Identifier" data type is:

http://gedcomx.org/v1/Identifier

properties

name description data type constraints
value The value of the identifier. URI REQUIRED.
type Enumerated value that identifies how the identifier is to be used and the nature of the resource to which the identifier resolves. Enumerated Value OPTIONAL. If provided, MUST identify an identifier type, and use of a known identifier type is RECOMMENDED. If no type is provided, the usage and nature of the identifier is application-specific.

known identifier types

The following identifier types are defined by GEDCOM X.

URI description
http://gedcomx.org/Primary The primary identifier for the resource. The value of the identifier MUST resolve to the instance of Subject to which the identifier applies.
http://gedcomx.org/Authority An identifier for the resource in an external authority or other expert system. The value of the identifier MUST resolve to a public, authoritative, source for information about the Subject to which the identifier applies.
http://gedcomx.org/Deprecated An identifier that has been relegated, deprecated, or otherwise downgraded. This identifier is commonly used as the result of a merge when what was once a primary identifier for a resource is no longer the primary identifier. The value of the identifier MUST resolve to the instance of Subject to which the identifier applies.

examples

  • An instance of Person with an identifier of type http://gedcomx.org/Primary and value "12345" is merged into an instance of Person with an identifier of type http://gedcomx.org/Primary and value "67890". Person "67890" assumes an identifier of type http://gedcomx.org/Deprecated and value "12345". The identifier type http://gedcomx.org/Deprecated is used because the merged person "12345" now has identifier of type http://gedcomx.org/Primary with value "67890".
  • A description of Salt Lake City, Utah, United States is provided using an instance of PlaceDescription. Salt Lake City is maintained in the Geographic Names Information System (GNIS), an external place authority. The description of Salt Lake City might identify the associated GNIS resource using an identifier of type http://gedcomx.org/Authority with value "http://geonames.usgs.gov/pls/gnispublic/f?p=gnispq:3:::NO::P3_FID:2411771".

3.2 The "Attribution" Data Type

The Attribution data type defines the data structure used to attribute who, when, and why to genealogical data. Data is attributed to the agent who made the latest significant change to the nature of the data being attributed. The definition of a "significant change" is outside the scope of this specification and is left to the implementer of the application.

The Granularity of Attribution

The granularity of data that is attributed varies widely from application to application. Some highly collaborative applications might take a fine-grained approach, tracking attribution at the level of names and facts. Single-user applications might simply provide attribution for a large set of data, such as an entire data tree. GEDCOM X explicitly defines attribution for top-level entities such as persons, relationships, and documents, as well as for some other specific data types such as notes and source references. However, GEDCOM X also recognizes attribution as an extension property that can be applied at a finer level of granularity. (For more information about extension properties, see Section 6). For all data types where attribution is explicitly recognized, it is an OPTIONAL property.

If data is not explicitly attributed, the attribution for the data is assumed to be the attribution for the containing data. For example, if no attribution is provided for the name of a person (as an extension property of the name), then the attribution for the name is assumed to be the attribution of the person that contains the name. If no attribution for the person is provided, the attribution is assumed to be the attribution for the data set that contains the person.

identifier

The identifier for the "Attribution" data type is:

http://gedcomx.org/v1/Attribution

properties

name description data type constraints
contributor Reference to the agent to whom the attributed data is attributed. URI OPTIONAL. If provided, MUST resolve to an instance of http://gedcomx.org/v1/Agent.
modified Timestamp of when the attributed data was contributed. timestamp OPTIONAL.
changeMessage A statement of why the attributed data is being provided by the contributor. string OPTIONAL.

3.3 The "Note" Data Type

The Note data type defines a note that was contributed from genealogical research.

Notes are not intended to contain genealogical conclusions. Notes are only associated with a single genealogical resource.

identifier

The identifier for the "Note" data type is:

http://gedcomx.org/v1/Note

properties

name description data type constraints
lang The locale identifier for the note. IETF BCP 47 locale tag OPTIONAL. If not provided, the locale is determined per Internationalization Considerations.
subject A subject or title for the note. string OPTIONAL.
text The text of the note. string REQUIRED.
attribution The attribution of this note. http://gedcomx.org/Attribution OPTIONAL. If not provided, the attribution of the containing resource of the note is assumed.

3.4 The "TextValue" Data Type

The TextValue data type defines a literal text value.

The TextValue data type does NOT support extension properties (see Extension Properties).

identifier

The identifier for the "TextValue" data type is:

http://gedcomx.org/v1/TextValue

properties

name description data type constraints
lang The locale identifier for the value of the text. IETF BCP 47 locale tag OPTIONAL. If not provided, the locale is determined per Internationalization Considerations.
value The text value. string REQUIRED.

3.5 The "SourceCitation" Data Type

The SourceCitation data type defines a container for the metadata necessary for an agent to identify a source(s).

identifier

The identifier for the "SourceCitation" data type is:

http://gedcomx.org/v1/SourceCitation

properties

name description data type constraints
lang The locale identifier for the bibliographic metadata. IETF BCP 47 locale tag OPTIONAL. If not provided, the locale is determined per Internationalization Considerations.
value The bibliographic metadata rendered as a full citation. string REQUIRED. This string is plain text, but MAY include an xhtml cite element. If the value includes a cite element, the text-level semantics defined for cite MUST apply—i.e., the element MUST represent the title of a work.

3.6 The "SourceReference" Data Type

The SourceReference data type defines a reference to a source description.

identifier

The identifier for the "SourceReference" data type is:

http://gedcomx.org/v1/SourceReference

properties

name description data type constraints
description Reference to a description of the target source. URI REQUIRED. MUST resolve to an instance of http://gedcomx.org/v1/SourceDescription.
attribution The attribution of this source reference. http://gedcomx.org/Attribution OPTIONAL. If not provided, the attribution of the containing resource of the source reference is assumed.

3.7 The "EvidenceReference" Data Type

The EvidenceReference data type defines a reference to data being used to derive the given instance of Subject. For example, an "evidence" Subject (i.e., the object holding the EvidenceReference instance) can refer to content extracted from a source (i.e., an "extracted" Subject) as information being used to derive the evidence expressed in this Subject.

identifier

The identifier for the "EvidenceReference" data type is:

http://gedcomx.org/v1/EvidenceReference

properties

name description data type constraints
resource Reference to the supporting data. URI REQUIRED. MUST resolve to an instance of http://gedcomx.org/v1/Subject.
attribution The attribution of this evidence reference. http://gedcomx.org/Attribution OPTIONAL. If not provided, the attribution of the containing resource of the source reference is assumed.

examples

  • An application allows a researcher to extract information from a single census record about a person, representing the information as a persona with an identifier "abcde". The researcher extracts additional information about the person from a birth certificate and the application assigns the resulting persona an identifier "fghij". As the researcher gathers and analyzes the information, he will create a (working) Person conclusion. When the researcher concludes that the person represented in "abcde" and in "fghij" are the same person, he will add two EvidenceReference instances to the working Person: one for "abcde" and one for "fghij".

3.8 The "OnlineAccount" Data Type

The OnlineAccount data type defines a description of an account for an online service provider.

identifier

The identifier for the OnlineAccount data type is:

http://gedcomx.org/v1/OnlineAccount

properties

name description data type constraints
serviceHomepage The URI identifying the online service provider that holds the account being described. URI REQUIRED.
accountName The name, label, or id that uniquely identifies the account maintained by the online service provider. string REQUIRED.

3.9 The "Address" Data Type

The Address data type defines a street or postal address of a person or organization.

identifier

The identifier for the Address data type is:

http://gedcomx.org/v1/Address

properties

name description data type constraints
value A full representation of the complete address. string OPTIONAL.
city The city. string OPTIONAL.
country The country. string OPTIONAL.
postalCode The postal code. string OPTIONAL.
stateOrProvince The state or province. string OPTIONAL.
street The street. string OPTIONAL.
street2 The street (second line). string OPTIONAL.
street3 The street (third line). string OPTIONAL.
street4 The street (fourth line). string OPTIONAL.
street5 The street (fifth line). string OPTIONAL.
street6 The street (sixth line). string OPTIONAL.

3.10 The "Conclusion" Data Type

The Conclusion data type defines the abstract concept for a basic genealogical data item.

In formal discussions of the genealogical research process, the term "conclusion" usually has a more specific meaning and is used to refer to an "accepted" hypothesis in accordance with the Genealogical Proof Standard. The name of the Conclusion data type is not meant to be associated with the definition of the term "conclusion" as it is described in the genealogical research process. Rather, the name refers to the notion that any information that is interpreted from an "original" is in some way a "conclusion"—even if the interpreter was diligent in representing the information verbatim as it was found in the original.

identifier

The identifier for the Conclusion data type is:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
id An identifier for the conclusion data. string OPTIONAL. The id is to be used as a "fragment identifier" as defined by RFC 3986, Section 3.5. As such, the constraints of the id are provided in the definition of the media type (e.g. XML, JSON) of the data structure.
lang The locale identifier for the conclusion. IETF BCP 47 locale tag OPTIONAL. If not provided, the locale is determined per Internationalization Considerations.
sources The list of references to the sources of related to this conclusion. List of http://gedcomx.org/v1/SourceReference. Order is preserved. OPTIONAL. Note that the sources referenced from conclusions are also considered to be sources of the entities that contain them. For example, a source associated with the Name of a Person is also source for the Person.
analysis Reference to a document containing analysis supporting this conclusion. URI OPTIONAL. If provided, MUST resolve to an instance of http://gedcomx.org/v1/Document of type http://gedcomx.org/Analysis.
notes A list of notes about this conclusion. List of http://gedcomx.org/Note OPTIONAL.
confidence Reference to a confidence level for this conclusion. Enumerated Value OPTIONAL. If provided, MUST identify a confidence level, and use of a known confidence level is RECOMMENDED.

3.10.1 Known Confidence Levels

The following confidence levels are defined by GEDCOM X.

URI description
http://gedcomx.org/High The contributor has a high degree of confidence that the assertion is true.
http://gedcomx.org/Medium The contributor has a medium degree of confidence that the assertion is true.
http://gedcomx.org/Low The contributor has a low degree of confidence that the assertion is true.

3.11 The "Subject" Data Type

The Subject data type defines the abstract concept of a genealogical subject.

A "subject" is something with a unique and intrinsic identity, such as a person or a location on the surface of the earth. We identify that subject in time and space using various supporting conclusions. For example, a person is a subject with supporting conclusions such as name, birth, gender, etc. We aggregate these supporting conclusions to form an apparently-unique identity by which we can distinguish our subject from all other possible subjects.

Note that a subject is itself a conclusion and can be used as a supporting conclusion for other subjects (via the evidence property). However, not all supporting conclusions are subjects. Researchers may research and debate a fact (e.g. where it took place, when it took place, the spelling of the name, etc.), but it is always within the context of a subject (e.g. where was the person born, when was the person born, how should the person's name be spelled).

identifier

The identifier for the Subject data type is:

http://gedcomx.org/v1/Subject

extension

This data type extends the following data type:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
extracted Whether this subject is to be constrained as an extracted conclusion. boolean OPTIONAL. Default: false. Refer to Extracted Conclusion Constraints.
evidence References to other subjects that support this subject. List of http://gedcomx.org/v1/EvidenceReference. Order is preserved. OPTIONAL. If provided, each reference MUST resolve to an instance of subject of the same type as this instance (e.g., if the subject is an instance of Person, all of its evidence references must resolve to instances of Person).
media References to multimedia resources for this subject, such as photos or videos, intended to provide additional context or illustration for the subject and not considered evidence supporting the identity of the subject or its supporting conclusions. List of http://gedcomx.org/v1/SourceReference OPTIONAL. Media references SHOULD be ordered by priority such that applications that wish to display a single media item (such as an image) MAY choose the first applicable media reference. Note that the SourceReference is used for multimedia references and therefore MUST resolve to a SourceDescription of the resource, which in turn provides a reference to the resource itself.
identifiers A list of identifiers for the subject. List of http://gedcomx.org/v1/Identifier. Order is preserved. OPTIONAL.
attribution The attribution of this subject. http://gedcomx.org/Attribution OPTIONAL. If not provided, the attribution of the containing data set (e.g. file) of the subject is assumed.

3.12 The "Gender" Data Type

The Gender data type defines a gender of a person.

identifier

The identifier for the Gender data type is:

http://gedcomx.org/v1/Gender

extension

This data type extends the following data type:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
type Enumerated value identifying the gender. Enumerated Value REQUIRED. MUST identify a gender type, and use of a known gender type is RECOMMENDED.

3.12.1 Known Gender Types

The following gender types are defined by GEDCOM X:

URI description
http://gedcomx.org/Male Male gender.
http://gedcomx.org/Female Female gender.
http://gedcomx.org/Unknown Unknown gender.

3.13 The "Name" Data Type

The Name data type defines a name of a person.

A Name is intended to represent a single variant of a person's name. This means that nicknames, spelling variations, or other names (often distinguishable by a name type) should be modeled with separate instances of Name.

The name forms of a name contain alternate representations of the name. A Name MUST contain at least one name form, presumably a representation of the name that is considered proper and well formed in the person's native, historical cultural context. Other name forms MAY be included, which can be used to represent this name in contexts where the native name form is not easily recognized and interpreted. Alternate forms are more likely in situations where conclusions are being analyzed across cultural context boundaries that have both language and writing script differences.

For example, a Korean name has a native Korean form, but can also have a Chinese form and a Roman/Latin form—three different name forms, but each representing the same name.

If more than one name form is provided, included name forms are presumed to be given in order of preference, with the most preferred name form in the first position in the list.

identifier

The identifier for the Name data type is:

http://gedcomx.org/v1/Name

extension

This data type extends the following data type:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
type Enumerated value identifying the name type. Enumerated Value OPTIONAL. If provided, MUST identify a name type, and use of a known name type is RECOMMENDED.
nameForms The name form(s) that best express this name, usually representations considered proper and well formed in the person's native, historical cultural context. List of http://gedcomx.org/v1/NameForm. Order is preserved. REQUIRED. At least one name form MUST be provided. All included name forms SHOULD be representations of the same name, and NOT variants of the name (i.e., not nicknames or spelling variations).
date The date of applicability of the name. http://gedcomx.org/v1/Date OPTIONAL.

examples

Consider the following: a Russian person with the birth name "Александр" (rendered as "Alexander" in English and in a Latin script) that also went by this name's common nickname, "Саша" (rendered as "Sasha" in English).

It is tempting to think that this situation should be modeled with one Name instance that has several alternate NameForms. The model is not designed to be used in this way. Instead, this person's names ought to be modeled such that the birth name and the nickname are modeled as two separate Name instances: one instance for the birth name, and one for the nickname. The type property MAY be provided to distinguish the birth name from the nickname. Each Name instance MAY have two NameForm instances: one with the native form of the name and another with the alternate form. Using an informal pseudo code, it might look something like the following:

Name1.type=http://gedcomx.org/BirthName
Name1.nameForms[0].fullText=Александр
Name1.nameForms[1].fullText=Alexander

Name2.type=http://gedcomx.org/Nickname
Name2.nameForms[0].fullText=Саша
Name2.nameForms[1].fullText=Sasha

3.13.1 Known Name Types

The following name types are defined by GEDCOM X:

URI description
http://gedcomx.org/BirthName Name given at birth.
http://gedcomx.org/MarriedName Name accepted at marriage.
http://gedcomx.org/AlsoKnownAs "Also known as" name.
http://gedcomx.org/Nickname Nickname.
http://gedcomx.org/AdoptiveName Name given at adoption.
http://gedcomx.org/FormalName A formal name, usually given to distinguish it from a name more commonly used.
http://gedcomx.org/ReligiousName A name given at a religious rite or ceremony.

3.14 The "Fact" Data Type

The Fact data type defines a data item that is presumed to be true about a specific subject, such as a person or relationship. To distinguish the concept of "fact" from "event", refer to Events Versus Facts.

identifier

The identifier for the Fact data type is:

http://gedcomx.org/v1/Fact

extension

This data type extends the following data type:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
type Enumerated value identifying the type of the fact. Enumerated Value REQUIRED. MUST identify a fact type, and use of a known fact type is RECOMMENDED.
date The date of applicability of the fact. http://gedcomx.org/v1/Date OPTIONAL.
place A reference to the place applicable to this fact. http://gedcomx.org/v1/PlaceReference OPTIONAL.
value The value of the fact. string OPTIONAL.
qualifiers Qualifiers to add additional details about the fact. List of http://gedcomx.org/v1/Qualifier OPTIONAL. If present, use of a known fact qualifier is RECOMMENDED.

3.14.1 Known Fact Types

The following fact types are defined by GEDCOM X:

URI description scope
http://gedcomx.org/Adoption A fact of a person's adoption. person
http://gedcomx.org/Birth A fact of a person's birth. person
http://gedcomx.org/Burial A fact of the burial of person's body after death. person
http://gedcomx.org/Christening A fact of a person's christening at birth. Note that this does not identify an adult christening. person
http://gedcomx.org/Death A fact of the death of a person. person
http://gedcomx.org/Residence A fact of a person's residence. person
http://gedcomx.org/Divorce The fact of a divorce of a couple. couple relationship
http://gedcomx.org/Marriage The fact of a marriage. couple relationship

In addition to these elements, processors SHOULD support any other elements defined by the GEDCOM X Fact Types specification.

3.14.2 Known Fact Qualifiers

The following fact qualifiers are defined by GEDCOM X:

name value
http://gedcomx.org/Age The age of a person at the event described by the fact.
http://gedcomx.org/Cause The cause of the fact, such as the cause of death.
http://gedcomx.org/Religion The religion associated with a religious event such as a baptism or excommunication.

3.15 The "EventRole" Data Type

The EventRole data type defines a role played in an event by a person.

identifier

The identifier for the EventRole data type is:

http://gedcomx.org/v1/EventRole

extension

This data type extends the following data type:

http://gedcomx.org/v1/Conclusion

properties

name description data type constraints
person Reference to the event participant. URI REQUIRED. MUST resolve to an instance of http://gedcomx.org/v1/Person.
type Enumerated value identifying the participant's role. Enumerated Value OPTIONAL. If provided, MUST identify a role type, and use of a known role type is RECOMMENDED.
details Details about the role of participant in the event. string OPTIONAL.

3.15.1 Known Role Types

The following role types are defined by GEDCOM X:

URI description
http://gedcomx.org/Principal The person is the principal person of the event. For example, the principal of a birth event is the person that was born.
http://gedcomx.org/Participant A participant in the event.
http://gedcomx.org/Official A person officiating the event.
http://gedcomx.org/Witness A witness of the event.

3.16 The "Date" Data Type

The Date data type defines a genealogical date.

identifier

The identifier for the Date data type is:

http://gedcomx.org/v1/Date

properties

name description data type constraints
original The original value of the date as supplied by the contributor. string OPTIONAL.
formal The standardized formal value of the date, formatted according to the GEDCOM X Date Format specification. GEDCOM X Date OPTIONAL.

3.17 The "PlaceReference" Data Type

The PlaceReference data type defines a reference to a description of a place.

identifier

The identifier for the PlaceReference data type is:

http://gedcomx.org/v1/PlaceReference

properties

name description data type constraints
original The original place name text as supplied by the contributor. string OPTIONAL.
descriptionRef A reference to a description of this place. URI OPTIONAL. If provided, MUST resolve to a PlaceDescription.

3.18 The "NamePart" Data Type

The NamePart data type is used to model a portion of a full name, including the terms that make up that portion. Some name parts may have qualifiers to provide additional semantic meaning to the name part (e.g., "given name" or "surname").

identifier

The identifier for the NamePart data type is:

http://gedcomx.org/v1/NamePart

properties

name description data type constraints
type Enumerated value identifying the type of the name part. Enumerated Value OPTIONAL. If provided, MUST identify a name part type, and use of a known name part type is RECOMMENDED.
value The term(s) from the name that make up this name part. string REQUIRED. A name part value MAY contain more than one term from the full name, such as in the name part "John Fitzgerald" from the full name "John Fitzgerald Kennedy". If multiple terms are detailed in a single NamePart, these terms SHOULD be separated using the name separator appropriate to the locale applicable to the containing name form.
qualifiers Qualifiers to add additional semantic meaning to the name part. List of http://gedcomx.org/v1/Qualifier OPTIONAL. If present, use of a name part qualifier defined by the GEDCOM X Name Part Qualifiers specification is RECOMMENDED.

3.18.1 Known Name Part Types

The following name part types are defined by GEDCOM X:

URI description
http://gedcomx.org/Prefix A name prefix.
http://gedcomx.org/Suffix A name suffix.
http://gedcomx.org/Given A given name.
http://gedcomx.org/Surname A surname.

3.19 The "NameForm" Data Type

The NameForm data type defines a representation of a name (a "name form") within a given cultural context, such as a given language and script.

As names are captured (both in records or in applications), the terms in the name are sometimes classified by type. For example, a certificate of death might prompt for "given name(s)" and "surname". The parts list can be used to represent the terms in the name that have been classified.

If both a full rendering of the name and a list of parts are provided, it NOT REQUIRED that every term in the fully rendered name appear in the list of parts.

Name parts in the parts list SHOULD be ordered in the natural order they would be used in the applicable cultural context.

If a full rendering of the name is not provided (i.e., the name has only been expressed in parts), a full rendering of the name MAY be derived (sans punctuation) by concatenating, in order, each name part value in the list of parts, separating each part with the name part separator appropriate for the applicable cultural context.

identifier

The identifier for the NameForm data type is:

http://gedcomx.org/v1/NameForm

properties

name description data type constraints
lang The locale identifier for the name form. IETF BCP 47 locale tag OPTIONAL. If not provided, the locale is determined per Internationalization Considerations.
fullText A full rendering of the name (or as much of the name as is known). string OPTIONAL. If provided, the name SHOULD be rendered as it would normally be spoken in the applicable cultural context.
parts Any identified name parts from the name. List of http://gedcomx.org/v1/NamePart. Order is preserved. OPTIONAL. If provided, the list SHOULD be ordered such that the parts are in the order they would normally be spoken in the applicable cultural context.

examples

Consider the following: the Russian name "Пётр Ильи́ч Чайко́вский" in the Cyrillic script, its Latin-script equivalent "Pyotr Ilyich Tchaikovsky", and its anglicised equivalent "Peter Ilyich Tchaikovsky". Using an informal pseudo code, these name forms might be modeled as follows:

NameForm1.locale=ru-Cyrl
NameForm1.fullText=Пётр Ильи́ч Чайко́вский
NameForm1.parts[0].type=http://gedcomx.org/Given
NameForm1.parts[0].value=Пётр
NameForm1.parts[0].qualifiers[0]=http://gedcomx.org/First
NameForm1.parts[1].type=http://gedcomx.org/Middle
NameForm1.parts[1].value=Ильи́ч
NameForm1.parts[1].qualifiers[0]=http://gedcomx.org/Middle
NameForm1.parts[2].type=http://gedcomx.org/Surname
NameForm1.parts[2].value=Чайко́вский

NameForm2.locale=ru-Latn
NameForm2.fullText=Pyotr Ilyich Tchaikovsky
NameForm2.parts[0].type=http://gedcomx.org/Given
NameForm2.parts[0].value=Pyotr
NameForm2.parts[0].qualifiers[0]=http://gedcomx.org/First
NameForm2.parts[1].type=http://gedcomx.org/Given
NameForm2.parts[1].value=Ilyich
NameForm2.parts[1].qualifiers[0]=http://gedcomx.org/Middle
NameForm2.parts[2].type=http://gedcomx.org/Surname
NameForm2.parts[2].value=Tchaikovsky

NameForm3.locale=en-Latn
NameForm3.fullText=Peter Ilyich Tchaikovsky
NameForm3.parts[0].type=http://gedcomx.org/Given
NameForm3.parts[0].value=Peter
NameForm3.parts[0].qualifiers[0]=http://gedcomx.org/First
NameForm3.parts[1].type=http://gedcomx.org/Given
NameForm3.parts[1].value=Ilyich
NameForm3.parts[1].qualifiers[0]=http://gedcomx.org/Middle
NameForm3.parts[2].type=http://gedcomx.org/Surname
NameForm3.parts[2].value=Tchaikovsky

3.20 The "Qualifier" Data Type

The Qualifier data type defines the data structure used to supply additional details, annotations, tags, or other qualifying data to a specific data element.

The Qualifier data type does NOT support extension properties (see Extension Properties).

identifier

The identifier for the "Qualifier" data type is:

http://gedcomx.org/v1/Qualifier

properties

name description data type constraints
name The name of the qualifier. Enumerated Value REQUIRED. It is RECOMMENDED that the qualifier name resolve to an element of a constrained vocabulary.
value The value of the qualifier. string OPTIONAL. If provided, the name MAY give the semantic meaning of the value.

4. Extracted Conclusion Constraints

GEDCOM X provides a specific definition for the term "extracted conclusion" that is used to refer to a set of constraints that MUST be applied to conclusion data that is identified as "extracted" using the extracted property (see Subject and Document).

When data is identified as "extracted", it means that the data is to be treated as having been extracted from a single source or record. Extracted data is distinguished from other data by the notion that it is intended to describe information about a subject found in a single source, as opposed to what a researcher or system believes to be true about the subject.

Applications MUST recognize the extracted property and SHOULD ensure that any modifications to the extracted data are aligned with the information that is provided by the specific (single) source, even if the source provides information that may conflict with information in other sources.

Data that is identified as "extracted" MUST conform to the following constraints:

  • The Subject or Document MUST NOT refer to more than one source description, including any supporting conclusions on the Subject.
  • All source references, including those on supporting conclusions, MUST resolve to the same source description, although each reference MAY contain distinct qualifying information such as attribution.

4.1 Persona

GEDCOM X provides a specific definition for the term "persona" that is used to refer to an instance of http://gedcomx.org/v1/Person that has been identified as an extracted conclusion.

5. Extensibility

Data types, properties, and enumerated values MAY be defined as extensions to the GEDCOM X Conceptual Model by external specifications. New data types, properties, and enumerated values MAY also be added by future versions of the GEDCOM X Conceptual Model or by other GEDCOM X specifications. Implementations of this version of the specification will not be able to process such extensions correctly and, in fact, will not be able to distinguish such extensions from error.

This section defines the constraints by which implementations of the GEDCOM X Conceptual Model SHOULD identify and process data types, properties, and enumerated values not defined by this version of GEDCOM X.

5.1 Data Type Extensions

New data types MAY be defined as extensions to GEDCOM X by providing the following:

  • A description of the data type.
  • An identifier for the data type.
  • The data type being extended by the data type, if any.
  • The properties of the data type.
  • Examples needed to clarify the usage of the data type, if any.

The base URI http://gedcomx.org/ is reserved for identifiers of data types defined by the GEDCOM X specification set. Data types defined outside the scope of the GEDCOM X specification set MUST NOT use the value http://gedcomx.org/ as a base URI for the data type identifier.

Specifications that define new data types as GEDCOM X extensions MUST be published and made freely available and compatible with the terms and constraints that govern the GEDCOM X Conceptual Model.

5.2 Enumerated Value Extensions

New enumerated values MAY be defined as extensions to GEDCOM X by providing the following:

  • An identifier for each enumerated value.
  • A description for each enumerated value.
  • An identification of which properties of which data types to which each enumerated value applies.

The base URI for enumerated values defined by the GEDCOM X specification set is http://gedcomx.org/. Enumerated values defined outside the scope of the GEDCOM X specification set MUST NOT use the value http://gedcomx.org/ as a base URI for the enumerated value identifier.

Specifications that define new enumerated values as GEDCOM X extensions MUST be published and made freely available and compatible with the terms and constraints that govern the GEDCOM X Conceptual Model.

5.2.1 User-Defined Enumerated Values

Some applications MAY allow enumerated values to be provided by a user. For example, a genealogy application may provide a feature that allows a user to describe a "custom" fact about a person when there doesn't exist a formally specified enumerated value.

In the case where a user has supplied a title or description instead of selecting a known enumerated value, GEDCOM X recognizes the data URI scheme as defined by RFC 2397.

5.3 Extension Properties

New properties MAY be defined as extensions to existing GEDCOM X data types by providing the following:

  • The data type to which the property applies.
  • A name of the property.
  • A description of the property.
  • The data type of the value of the property.
  • Any constraints that are applicable to the property.

Extension properties MUST NOT be defined on data types that explicitly restrict extension properties.

Extension properties MUST NOT be defined as "REQUIRED".

Specifications that define new properties as GEDCOM X extensions MUST be published and made freely available and compatible with the terms and constraints that govern the GEDCOM X Conceptual Model.

5.4 Processing Extensions

If extensions are used, extensions MUST be provided such that GEDCOM X implementations can bypass the extension and continue processing. GEDCOM X implementations that encounter extensions in a location that is legal according to this specification SHOULD NOT stop processing or signal an error, although implementations MAY signal nonfatal warnings. A GEDCOM X implementation MAY be able to process the extension correctly and choose to do so. Otherwise, GEDCOM X implementations MAY bypass the extensions and MUST NOT change their behavior as a result of the presence of the extension.

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