--- a/base/rendered.txt
+++ b/head/rendered.txt
@@ -159,11 +159,11 @@
 A Host Info object as defined in Host Info identifying the
 operator of this catalog.
 
-metadata
-
-An open map of string keys to arbitrary values for custom or
-non-standard metadata. See Metadata Extensibility
-for key naming conventions.
+extensions
+
+An array of Extension objects containing custom, vendor-specific, or
+non-standard fields. See Extensions for definitions and
+official extension types.
 
 Host Info
 
@@ -315,9 +315,9 @@
 A string containing an ISO 8601 [[RFC3339]] timestamp indicating
 when this entry was last modified.
 
-metadata
-
-An open map of string keys to arbitrary values for custom data.
+extensions
+
+An array of Extension objects containing custom data.
 
 publisher
 
@@ -510,10 +510,9 @@
 over the Trust Manifest content. This enables integrity verification
 of the trust metadata independent of the artifact.
 
-metadata
-
-An open map of string keys to arbitrary values for extending trust
-metadata.
+extensions
+
+An array of Extension objects for extending trust metadata.
 
 For example, a Trust Manifest with identity, attestations, and
 provenance:
@@ -857,42 +856,43 @@
 RECOMMENDED. Implementations MAY support deeper nesting but SHOULD
 document their limit.
 
-Metadata Extensibility
-
-The metadata property appears on the AI Catalog top-level object,
+Extensions
+
+The extensions property appears on the AI Catalog top-level object,
 on Catalog Entry objects, and on Trust Manifest objects. It provides
 a single, well-defined extension point for custom or vendor-specific
 properties.
 
-Key Naming
-
-Metadata keys MUST be non-empty strings. To avoid collisions between
-independent publishers, the following conventions are RECOMMENDED:
-
-Reverse-DNS prefix for vendor-specific keys:
+Format and Key Naming
+
+The extensions field is an array of objects. Each object MUST contain
+a type string and a data object.
+
+To avoid collisions between independent publishers, the type field MUST
+be a valid URL or a reverse-DNS string:
+
+Reverse-DNS prefix for vendor-specific extensions:
 com.example.confidenceScore, io.acme.deploymentRegion.
 
-Short, unqualified names for keys the publisher considers
-broadly useful and unlikely to conflict: repository, homepage,
-license.
-
-Avoid keys that duplicate defined catalog fields (displayName,
-description, tags, version). Consumers MAY ignore metadata
-entries that shadow standard fields.
-
-Reserved Keys
-
-No metadata keys are reserved by this specification. Future
-specification versions MAY promote commonly used metadata keys into
-standard fields. When this occurs, the metadata key SHOULD be
-retained for backward compatibility and the standard field takes
-precedence.
-
-Value Types
-
-Metadata values MAY be any valid JSON type (string, number, boolean,
-array, object, null). Consumers that do not recognize a metadata key
-SHOULD ignore it.
+URL prefix for publicly accessible extension schemas:
+https://cisco.com/extensions/security-scan.
+
+Consumers that do not recognize an extension type MUST ignore it without
+throwing an error.
+
+Official Extensions
+
+While publishers are free to create custom extensions, this specification
+defines a set of "Official" known types for commonly requested schemas:
+
+Metadata (https://ai-catalog.org/extensions/metadata)
+- Used to store generic, schemaless key-value pairs (replacing the legacy metadata field).
+
+SBOM (https://ai-catalog.org/extensions/sbom)
+- Used to embed or link to a Software Bill of Materials for the catalog entry.
+
+As custom extensions become highly popular, the AI-Catalog TSC may promote
+them to Official Known Types or core standard fields in future specification versions.
 
 Version Handling
 
@@ -1380,7 +1380,12 @@
 specVersion: text,
 ? host: HostInfo,
 entries: [* CatalogEntry],
-? metadata: { * text => any }
+? extensions: [* Extension]
+}
+
+Extension = {
+type: text,
+data: any
 }
 
 HostInfo = {
@@ -1402,7 +1407,7 @@
 ? publisher: Publisher,
 ? trustManifest: TrustManifest,
 ? updatedAt: tdate,
-? metadata: { * text => any }
+? extensions: [* Extension]
 }
 
 Publisher = {
@@ -1422,7 +1427,7 @@
 ? privacyPolicyUrl: text,
 ? termsOfServiceUrl: text,
 ? signature: text,
-? metadata: { * text => any }
+? extensions: [* Extension]
 }
 
 TrustSchema = {