Spatial Index Cell - Definitions - Integrated Campaign Registry (ICR) Implementation Guide v0.1.0

Integrated Campaign Registry (ICR) Implementation Guide - Local Development build (v0.1.0) built by the FHIR (HL7® FHIR® Standard) Build Tools. See the Directory of published versions

Extension: SpatialIndex - Detailed Descriptions

Draft as of 2026-09-06

Definitions for the spatial-index extension.

Key Elements Table
Differential Elements Table
Snapshot Elements Table

Guidance on how to interpret the contents of this table can be foundhere

0. Extension
Definition	A spatial index cell derived from the Location's position: which tiling scheme (quadkey \| h3 \| geohash), at what level (quadkey zoom / H3 resolution / geohash precision), and the cell key. Repeatable — a point carries at most one cell per scheme and level (ICRLocation invariant icr-loc-spatial-one-per-level); several schemes and levels may coexist. Quadkey and geohash cells are prefix-hierarchical, so a FHIR string search on the cell (Location?quadkey=0313…) answers 'every point inside this coarser tile' with no geometry engine; H3 cells join on exact match. Derived data: written by the loader (kiln) at import or as a backfill edit, recomputed whenever the position changes, never hand-entered. Not an identifier — many places share a cell (spatial-index round, Sep 2026). Optional Extension Element - found in all resources.
Short	Spatial Index CellOptional Extensions Element
Control	0..* This element is affected by the following invariants: ele-1
Is Modifier	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`) icr-spatial-quadkey: A quadkey cell is base-4 digits, exactly level characters long, level 1–23. (`extension.where(url = 'system').value = 'quadkey' implies (extension.where(url = 'cell').value.matches('^[0-3]+$') and extension.where(url = 'cell').value.length() = extension.where(url = 'level').value and extension.where(url = 'level').value >= 1 and extension.where(url = 'level').value <= 23)`) icr-spatial-h3: An H3 cell is a 15-hex-character index, level (resolution) 0–15. (`extension.where(url = 'system').value = 'h3' implies (extension.where(url = 'cell').value.matches('^[0-9a-f]{15}$') and extension.where(url = 'level').value <= 15)`) icr-spatial-geohash: A geohash cell is base-32 characters, exactly level characters long, level 1–12. (`extension.where(url = 'system').value = 'geohash' implies (extension.where(url = 'cell').value.matches('^[0-9b-hjkmnp-z]+$') and extension.where(url = 'cell').value.length() = extension.where(url = 'level').value and extension.where(url = 'level').value >= 1 and extension.where(url = 'level').value <= 12)`) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
2. Extension.extension
Definition	An Extension 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.
Short	ExtensionAdditional content defined by implementations
Comments	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.
Control	30..*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
4. Extension.extension:system
Slice Name	system
Definition	An Extension
Short	quadkey \| h3 \| geohashAdditional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Must Support	true
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
6. Extension.extension:system.extension
Definition	An Extension 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.
Short	ExtensionAdditional content defined by implementations
Comments	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.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
8. Extension.extension:system.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`system`
10. Extension.extension:system.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..1
Binding	The codes SHALL be taken from For codes, see ICR Spatial Index Scheme (required to `https://icr.healthcampaigns.org/ValueSet/icr-spatial-index`)
Type	code, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, Coding, SampledData, id, positiveInt, Distance, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, CodeableConcept, ParameterDefinition, dateTime, string, Contributor, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
12. Extension.extension:level
Slice Name	level
Definition	An Extension
Short	Quadkey zoom (1–23), H3 resolution (0–15), geohash precision (1–12) — explicit even where recoverable from the cell, so 'every point indexed at level 18' is a plain queryAdditional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Must Support	true
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
14. Extension.extension:level.extension
Definition	An Extension 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.
Short	ExtensionAdditional content defined by implementations
Comments	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.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
16. Extension.extension:level.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`level`
18. Extension.extension:level.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..1
Type	unsignedInt, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, Coding, SampledData, id, positiveInt, Distance, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, CodeableConcept, ParameterDefinition, dateTime, code, string, Contributor, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, Signature, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
20. Extension.extension:cell
Slice Name	cell
Definition	An Extension
Short	The cell key in the scheme's canonical string form (quadkey: base-4 digits; h3: 15 hex chars; geohash: base-32)Additional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Must Support	true
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
22. Extension.extension:cell.extension
Definition	An Extension 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.
Short	ExtensionAdditional content defined by implementations
Comments	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.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
24. Extension.extension:cell.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`cell`
26. Extension.extension:cell.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..1
Type	string, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, Coding, SampledData, id, positiveInt, Distance, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, CodeableConcept, ParameterDefinition, dateTime, code, Contributor, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
28. Extension.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`https://icr.healthcampaigns.org/StructureDefinition/spatial-index`
30. Extension.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..01
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, Reference, SampledData, Signature, Timing, ContactDetail, Contributor, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))

Guidance on how to interpret the contents of this table can be foundhere

0. Extension
Definition	A spatial index cell derived from the Location's position: which tiling scheme (quadkey \| h3 \| geohash), at what level (quadkey zoom / H3 resolution / geohash precision), and the cell key. Repeatable — a point carries at most one cell per scheme and level (ICRLocation invariant icr-loc-spatial-one-per-level); several schemes and levels may coexist. Quadkey and geohash cells are prefix-hierarchical, so a FHIR string search on the cell (Location?quadkey=0313…) answers 'every point inside this coarser tile' with no geometry engine; H3 cells join on exact match. Derived data: written by the loader (kiln) at import or as a backfill edit, recomputed whenever the position changes, never hand-entered. Not an identifier — many places share a cell (spatial-index round, Sep 2026).
Short	Spatial Index Cell
Invariants	icr-spatial-quadkey: A quadkey cell is base-4 digits, exactly level characters long, level 1–23. (`extension.where(url = 'system').value = 'quadkey' implies (extension.where(url = 'cell').value.matches('^[0-3]+$') and extension.where(url = 'cell').value.length() = extension.where(url = 'level').value and extension.where(url = 'level').value >= 1 and extension.where(url = 'level').value <= 23)`) icr-spatial-h3: An H3 cell is a 15-hex-character index, level (resolution) 0–15. (`extension.where(url = 'system').value = 'h3' implies (extension.where(url = 'cell').value.matches('^[0-9a-f]{15}$') and extension.where(url = 'level').value <= 15)`) icr-spatial-geohash: A geohash cell is base-32 characters, exactly level characters long, level 1–12. (`extension.where(url = 'system').value = 'geohash' implies (extension.where(url = 'cell').value.matches('^[0-9b-hjkmnp-z]+$') and extension.where(url = 'cell').value.length() = extension.where(url = 'level').value and extension.where(url = 'level').value >= 1 and extension.where(url = 'level').value <= 12)`)
2. Extension.extension
Control	3..?
4. Extension.extension:system
Slice Name	system
Short	quadkey \| h3 \| geohash
Control	1..1
Must Support	true
6. Extension.extension:system.extension
Control	0..0
8. Extension.extension:system.url
Fixed Value	`system`
10. Extension.extension:system.value[x]
Binding	The codes SHALL be taken from ICR Spatial Index Scheme (required to `https://icr.healthcampaigns.org/ValueSet/icr-spatial-index`)
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
12. Extension.extension:level
Slice Name	level
Short	Quadkey zoom (1–23), H3 resolution (0–15), geohash precision (1–12) — explicit even where recoverable from the cell, so 'every point indexed at level 18' is a plain query
Control	1..1
Must Support	true
14. Extension.extension:level.extension
Control	0..0
16. Extension.extension:level.url
Fixed Value	`level`
18. Extension.extension:level.value[x]
Type	unsignedInt
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
20. Extension.extension:cell
Slice Name	cell
Short	The cell key in the scheme's canonical string form (quadkey: base-4 digits; h3: 15 hex chars; geohash: base-32)
Control	1..1
Must Support	true
22. Extension.extension:cell.extension
Control	0..0
24. Extension.extension:cell.url
Fixed Value	`cell`
26. Extension.extension:cell.value[x]
Type	string
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
28. Extension.url
Fixed Value	`https://icr.healthcampaigns.org/StructureDefinition/spatial-index`
30. Extension.value[x]
Control	0..0

Guidance on how to interpret the contents of this table can be foundhere

0. Extension
Definition	A spatial index cell derived from the Location's position: which tiling scheme (quadkey \| h3 \| geohash), at what level (quadkey zoom / H3 resolution / geohash precision), and the cell key. Repeatable — a point carries at most one cell per scheme and level (ICRLocation invariant icr-loc-spatial-one-per-level); several schemes and levels may coexist. Quadkey and geohash cells are prefix-hierarchical, so a FHIR string search on the cell (Location?quadkey=0313…) answers 'every point inside this coarser tile' with no geometry engine; H3 cells join on exact match. Derived data: written by the loader (kiln) at import or as a backfill edit, recomputed whenever the position changes, never hand-entered. Not an identifier — many places share a cell (spatial-index round, Sep 2026).
Short	Spatial Index Cell
Control	0..* This element is affected by the following invariants: ele-1
Is Modifier	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`) icr-spatial-quadkey: A quadkey cell is base-4 digits, exactly level characters long, level 1–23. (`extension.where(url = 'system').value = 'quadkey' implies (extension.where(url = 'cell').value.matches('^[0-3]+$') and extension.where(url = 'cell').value.length() = extension.where(url = 'level').value and extension.where(url = 'level').value >= 1 and extension.where(url = 'level').value <= 23)`) icr-spatial-h3: An H3 cell is a 15-hex-character index, level (resolution) 0–15. (`extension.where(url = 'system').value = 'h3' implies (extension.where(url = 'cell').value.matches('^[0-9a-f]{15}$') and extension.where(url = 'level').value <= 15)`) icr-spatial-geohash: A geohash cell is base-32 characters, exactly level characters long, level 1–12. (`extension.where(url = 'system').value = 'geohash' implies (extension.where(url = 'cell').value.matches('^[0-9b-hjkmnp-z]+$') and extension.where(url = 'cell').value.length() = extension.where(url = 'level').value and extension.where(url = 'level').value >= 1 and extension.where(url = 'level').value <= 12)`)
2. Extension.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1
Type	string
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
4. Extension.extension
Definition	An Extension
Short	Extension
Control	3..*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
6. Extension.extension:system
Slice Name	system
Definition	An Extension
Short	quadkey \| h3 \| geohash
Control	1..1
Type	Extension
Is Modifier	false
Must Support	true
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
8. Extension.extension:system.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1
Type	string
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
10. Extension.extension:system.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
12. Extension.extension:system.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`system`
14. Extension.extension:system.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..1
Binding	The codes SHALL be taken from ICR Spatial Index Scheme (required to `https://icr.healthcampaigns.org/ValueSet/icr-spatial-index`)
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
16. Extension.extension:level
Slice Name	level
Definition	An Extension
Short	Quadkey zoom (1–23), H3 resolution (0–15), geohash precision (1–12) — explicit even where recoverable from the cell, so 'every point indexed at level 18' is a plain query
Control	1..1
Type	Extension
Is Modifier	false
Must Support	true
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
18. Extension.extension:level.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1
Type	string
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
20. Extension.extension:level.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
22. Extension.extension:level.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`level`
24. Extension.extension:level.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..1
Type	unsignedInt
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
26. Extension.extension:cell
Slice Name	cell
Definition	An Extension
Short	The cell key in the scheme's canonical string form (quadkey: base-4 digits; h3: 15 hex chars; geohash: base-32)
Control	1..1
Type	Extension
Is Modifier	false
Must Support	true
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
28. Extension.extension:cell.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1
Type	string
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
30. Extension.extension:cell.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
32. Extension.extension:cell.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`cell`
34. Extension.extension:cell.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..1
Type	string
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
36. Extension.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`https://icr.healthcampaigns.org/StructureDefinition/spatial-index`
38. Extension.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..0
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, Reference, SampledData, Signature, Timing, ContactDetail, Contributor, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)