diff --git a/enumeration-set/extension/enumset-Presence.yaml b/enumeration-set/extension/enumset-Presence.yaml
new file mode 100644
index 00000000..3f71e973
--- /dev/null
+++ b/enumeration-set/extension/enumset-Presence.yaml
@@ -0,0 +1,17 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: enumeration set
+
+uri: https://github.com/glamberson/gedcom-occurrences/enumset-Presence
+
+enumeration values:
+  - "https://github.com/glamberson/gedcom-occurrences/enum-Present"
+  - "https://github.com/glamberson/gedcom-occurrences/enum-Absent"
+  - "https://github.com/glamberson/gedcom-occurrences/enum-Unknown"
+
+contact: "https://github.com/glamberson/gedcom-occurrences"
+
+documentation: [https://github.com/glamberson/gedcom-occurrences]
+...
diff --git a/enumeration/extension/enum-Absent.yaml b/enumeration/extension/enum-Absent.yaml
new file mode 100644
index 00000000..b1e8c0ba
--- /dev/null
+++ b/enumeration/extension/enum-Absent.yaml
@@ -0,0 +1,19 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: enumeration
+
+uri: https://github.com/glamberson/gedcom-occurrences/enum-Absent
+
+extension tags: [_ABSENT]
+
+specification:
+  - Absent
+  - Person was listed or referenced but not physically present
+
+value of:
+  - https://github.com/glamberson/gedcom-occurrences/enumset-Presence
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
diff --git a/enumeration/extension/enum-Present.yaml b/enumeration/extension/enum-Present.yaml
new file mode 100644
index 00000000..86a266bc
--- /dev/null
+++ b/enumeration/extension/enum-Present.yaml
@@ -0,0 +1,19 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: enumeration
+
+uri: https://github.com/glamberson/gedcom-occurrences/enum-Present
+
+extension tags: [_PRESENT]
+
+specification:
+  - Present
+  - Person was physically present at the occurrence
+
+value of:
+  - https://github.com/glamberson/gedcom-occurrences/enumset-Presence
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
diff --git a/enumeration/extension/enum-Unknown.yaml b/enumeration/extension/enum-Unknown.yaml
new file mode 100644
index 00000000..932563ab
--- /dev/null
+++ b/enumeration/extension/enum-Unknown.yaml
@@ -0,0 +1,19 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: enumeration
+
+uri: https://github.com/glamberson/gedcom-occurrences/enum-Unknown
+
+extension tags: [_UNKNOWN]
+
+specification:
+  - Unknown
+  - Presence status cannot be determined from the source
+
+value of:
+  - https://github.com/glamberson/gedcom-occurrences/enumset-Presence
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
diff --git a/registry_tools/GEDCOM.io b/registry_tools/GEDCOM.io
index da76dfe9..45791f0a 160000
--- a/registry_tools/GEDCOM.io
+++ b/registry_tools/GEDCOM.io
@@ -1 +1 @@
-Subproject commit da76dfe933b22833035e005e7092ba1a91be0140
+Subproject commit 45791f0a61ae7375bca211019fdaeb12179c3925
diff --git a/structure/extension/_ATTR.yaml b/structure/extension/_ATTR.yaml
new file mode 100644
index 00000000..054920d8
--- /dev/null
+++ b/structure/extension/_ATTR.yaml
@@ -0,0 +1,36 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: structure
+
+uri: https://github.com/glamberson/gedcom-occurrences/_ATTR
+
+extension tags:
+  - _ATTR
+
+specification:
+  - Custom Attribute
+  - |
+    A custom attribute for an occurrence or participant. This allows
+    applications to add specific attributes that aren't covered by
+    standard GEDCOM structures, ensuring data preservation during
+    import/export cycles.
+    
+    The attribute name is in the payload, and the value is in the
+    required _VALUE substructure.
+
+label: Custom Attribute
+
+payload: http://www.w3.org/2001/XMLSchema#string
+
+substructures:
+  "https://gedcom.io/terms/v7/NOTE": "{0:M}"
+  "https://github.com/glamberson/gedcom-occurrences/_VALUE": "{1:1}"
+
+superstructures:
+  "https://github.com/glamberson/gedcom-occurrences/_OCUR": "{0:M}"
+  "https://github.com/glamberson/gedcom-occurrences/_OCREF": "{0:M}"
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
\ No newline at end of file
diff --git a/structure/extension/_OCREF.yaml b/structure/extension/_OCREF.yaml
new file mode 100644
index 00000000..37ab1c26
--- /dev/null
+++ b/structure/extension/_OCREF.yaml
@@ -0,0 +1,41 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: structure
+
+uri: https://github.com/glamberson/gedcom-occurrences/_OCREF
+
+extension tags:
+  - _OCREF
+
+specification:
+  - Occurrence Reference
+  - |
+    A reference from an individual or family to an occurrence record (_OCUR).
+    This structure contains all participant-specific data such as role, age,
+    and participation details.
+    
+    In the container-only model (v0.2.0+), all participant data is stored
+    exclusively in _OCREF structures to avoid data duplication and synchronization
+    issues.
+
+label: Occurrence Reference
+
+payload: "@<https://github.com/glamberson/gedcom-occurrences/_OCUR>@"
+
+substructures:
+  "https://gedcom.io/terms/v7/AGE": "{0:1}"
+  "https://gedcom.io/terms/v7/NOTE": "{0:M}"
+  "https://gedcom.io/terms/v7/ROLE": "{1:1}"
+  "https://gedcom.io/terms/v7/SNOTE": "{0:M}"
+  "https://gedcom.io/terms/v7/SOUR": "{0:M}"
+  "https://github.com/glamberson/gedcom-occurrences/_ATTR": "{0:M}"
+  "https://github.com/glamberson/gedcom-occurrences/_PRESENCE": "{0:1}"
+
+superstructures:
+  "https://gedcom.io/terms/v7/record-FAM": "{0:M}"
+  "https://gedcom.io/terms/v7/record-INDI": "{0:M}"
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
\ No newline at end of file
diff --git a/structure/extension/_OCUR.yaml b/structure/extension/_OCUR.yaml
new file mode 100644
index 00000000..235bb05f
--- /dev/null
+++ b/structure/extension/_OCUR.yaml
@@ -0,0 +1,51 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: structure
+
+uri: https://github.com/glamberson/gedcom-occurrences/_OCUR
+
+extension tags:
+  - _OCUR
+
+specification:
+  - Occurrence Record
+  - |
+    An _OCUR record represents an occurrence as an independent, first-class object
+    that can involve multiple participants with different roles. This allows
+    the same occurrence (such as a census, burial, or ceremony) to be referenced
+    by multiple people without duplication of occurrence data.
+    
+    Unlike embedded events (EVEN) in INDI or FAM records, _OCUR records exist at
+    the top level and are referenced using _OCREF from participants.
+    
+    This extension addresses the synchronization problems that occur when multiple
+    people participate in the same event, providing a clean separation between
+    event data (date, place, type) and participation data (role, age).
+
+label: Occurrence
+
+payload: null
+
+substructures:
+  "https://gedcom.io/terms/v7/ADDR": "{0:1}"
+  "https://gedcom.io/terms/v7/AGNC": "{0:1}"
+  "https://gedcom.io/terms/v7/CAUS": "{0:1}"
+  "https://gedcom.io/terms/v7/CHAN": "{0:1}"
+  "https://gedcom.io/terms/v7/DATE": "{0:1}"
+  "https://gedcom.io/terms/v7/EXID": "{0:M}"
+  "https://gedcom.io/terms/v7/NOTE": "{0:M}"
+  "https://gedcom.io/terms/v7/OBJE": "{0:M}"
+  "https://gedcom.io/terms/v7/PLAC": "{0:1}"
+  "https://gedcom.io/terms/v7/RELI": "{0:1}"
+  "https://gedcom.io/terms/v7/SNOTE": "{0:M}"
+  "https://gedcom.io/terms/v7/SOUR": "{0:M}"
+  "https://gedcom.io/terms/v7/TYPE": "{1:1}"
+  "https://gedcom.io/terms/v7/UID": "{0:M}"
+  "https://github.com/glamberson/gedcom-occurrences/_PART": "{0:M}"
+
+superstructures: {}
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
\ No newline at end of file
diff --git a/structure/extension/_PART.yaml b/structure/extension/_PART.yaml
new file mode 100644
index 00000000..79ea41a9
--- /dev/null
+++ b/structure/extension/_PART.yaml
@@ -0,0 +1,35 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: structure
+
+uri: https://github.com/glamberson/gedcom-occurrences/_PART
+
+extension tags:
+  - _PART
+
+specification:
+  - Occurrence Participant
+  - |
+    A reference to an individual or family who participated in an occurrence.
+    This structure is used within _OCUR records to list all participants.
+    The actual participation details (role, age, etc.) are stored in the
+    participant's _OCREF structure, not here.
+    
+    This design maintains a clean separation between occurrence data and
+    participant-specific data.
+
+label: Participant Reference
+
+payload: "@<https://gedcom.io/terms/v7/record-INDI>@ | @<https://gedcom.io/terms/v7/record-FAM>@"
+
+substructures:
+  "https://gedcom.io/terms/v7/NOTE": "{0:M}"
+  "https://github.com/glamberson/gedcom-occurrences/_PRESENCE": "{0:1}"
+
+superstructures:
+  "https://github.com/glamberson/gedcom-occurrences/_OCUR": "{0:M}"
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
diff --git a/structure/extension/_PRESENCE.yaml b/structure/extension/_PRESENCE.yaml
new file mode 100644
index 00000000..1f407638
--- /dev/null
+++ b/structure/extension/_PRESENCE.yaml
@@ -0,0 +1,34 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: structure
+
+uri: https://github.com/glamberson/gedcom-occurrences/_PRESENCE
+
+extension tags:
+  - _PRESENCE
+
+specification:
+  - Presence Status
+  - |
+    Indicates the presence status of a participant in an occurrence.
+    Used to explicitly note when someone was absent from an event they
+    were expected to attend, or when their presence is uncertain.
+    
+    This is particularly useful for census records, family gatherings,
+    or other events where absence is notable.
+
+label: Presence Status
+
+payload: https://github.com/glamberson/gedcom-occurrences/enumset-Presence
+
+substructures:
+  "https://gedcom.io/terms/v7/NOTE": "{0:M}"
+
+superstructures:
+  "https://github.com/glamberson/gedcom-occurrences/_OCREF": "{0:1}"
+  "https://github.com/glamberson/gedcom-occurrences/_PART": "{0:1}"
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...
\ No newline at end of file
diff --git a/structure/extension/_VALUE.yaml b/structure/extension/_VALUE.yaml
new file mode 100644
index 00000000..d29db5bd
--- /dev/null
+++ b/structure/extension/_VALUE.yaml
@@ -0,0 +1,29 @@
+%YAML 1.2
+---
+lang: en-US
+
+type: structure
+
+uri: https://github.com/glamberson/gedcom-occurrences/_VALUE
+
+extension tags:
+  - _VALUE
+
+specification:
+  - Attribute Value
+  - |
+    The value for a custom attribute defined by _ATTR. This structure
+    contains the actual value of the attribute, while the attribute
+    name is stored in the _ATTR payload.
+
+label: Value
+
+payload: http://www.w3.org/2001/XMLSchema#string
+
+substructures: {}
+
+superstructures:
+  "https://github.com/glamberson/gedcom-occurrences/_ATTR": "{1:1}"
+
+contact: https://github.com/glamberson/gedcom-occurrences
+...