diff --git a/src/lifecycle.md b/src/lifecycle.md
index 1829328..f3b3eef 100644
--- a/src/lifecycle.md
+++ b/src/lifecycle.md
@@ -1,10 +1,21 @@
 # Lifecycle Specification
 
-## Version History
+## Abstract
 
-| Version | Date | Notes |
-| ---- | ---- | ---- |
-| 1.0.0 | TBD | Initial release |
+TODO: One or two sentences summarizing what the Lifecycle Object is and the
+problem it solves.
+
+## Version 1.0.0
+
+The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
+"SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this
+document are to be interpreted as described in [BCP 14](https://tools.ietf.org/html/bcp14)
+[RFC2119](https://tools.ietf.org/html/rfc2119)
+[RFC8174](https://tools.ietf.org/html/rfc8174) when, and only when, they
+appear in all capitals, as shown here.
+
+TODO: Confirm license. OAI companion specifications typically use the
+[Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.html).
 
 ## Introduction
 
@@ -21,50 +32,79 @@ features:
     # Lifecycle Object fields here
 ```
 
-Compatibility between versions of this specification and versions of the OpenAPI
-Specification is determined by publication date. The rules for determining
-compatible version pairs are documented in [TODO: link or section].
+Compatibility between versions of this specification and versions of the
+OpenAPI Specification is determined by publication date. The rules for
+determining compatible version pairs are documented under
+[Compatibility](#compatibility).
 
 ## Definitions
 
-### Lifecycle Object
+### Lifecycle
 
-A **Lifecycle Object** is ...
-
-#### Fixed Fields
-
-| Field Name | Type | Description |
-| ---- | ---- | ---- |
-| TODO | TODO | TODO |
+TODO: A short, informal description of what a Lifecycle is conceptually —
+not the field-by-field schema. The Fixed Fields for the Lifecycle Object
+live under [Schema](#schema) below.
 
 ### Schema Object
 
-A **Schema Object** is a JSON Schema schema as defined by the OpenAPI Specification
-in use. Within this document, Schema Objects behave according to the OAS dialect
-in effect in the containing OpenAPI document.
+A **Schema Object** is a JSON Schema schema as defined by the OpenAPI
+Specification in use. Within this document, Schema Objects behave according
+to the OAS dialect in effect in the containing OpenAPI document.
 
 ## Specification
 
-### Version `1.0`
+### Versions
 
-This document is the Lifecycle Specification version 1.0.0.
+The Lifecycle Specification is versioned using a `major`.`minor`.`patch`
+scheme. The `major`.`minor` portion of the version string (for example,
+`1.0`) designates the Lifecycle feature set in effect. `patch` releases
+address errors in, or provide clarifications to, this document without
+changing the feature set; tooling SHOULD treat all patch releases within a
+`major`.`minor` line as equivalent.
 
-### Notation
+#### Compatibility
 
-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 [RFC2119](https://tools.ietf.org/html/rfc2119).
+TODO: Document the rules for determining which versions of this
+specification are compatible with which versions of the OpenAPI
+Specification (referenced from
+[Relationship to the OpenAPI Specification](#relationship-to-the-openapi-specification)
+above).
 
 ### Schema
 
-Implementations that validate Lifecycle Objects MUST use the schema published at
-`https://spec.openapis.org/lifecycle/1.0/schema/WORK-IN-PROGRESS`.
+In the following description, if a field is not explicitly **REQUIRED** or
+described with a MUST or SHALL, it can be considered OPTIONAL.
 
-When validating a Lifecycle Object within an OpenAPI document, the Schema Object
-schema in effect is determined by the OAS dialect declared in that document.
-Standalone validation of Lifecycle Objects uses the standard JSON Schema
-2020-12 dialect for Schema Object positions.
+#### Lifecycle Object
 
-## Appendix A — Revision History
+A **Lifecycle Object** is ...
 
-TODO: Document notable changes between versions.
+##### Fixed Fields
+
+| Field Name | Type | Description |
+| ---- | ---- | ---- |
+| TODO | TODO | TODO |
+
+This object MAY be extended with [Specification Extensions](#specification-extensions).
+
+Implementations that validate Lifecycle Objects MUST use the schema
+published at `https://spec.openapis.org/lifecycle/1.0/schema/WORK-IN-PROGRESS`.
+When validating a Lifecycle Object within an OpenAPI document, the Schema
+Object schema in effect is determined by the OAS dialect declared in that
+document. Standalone validation of Lifecycle Objects uses the standard JSON
+Schema 2020-12 dialect for Schema Object positions.
+
+TODO: Replace `WORK-IN-PROGRESS` with a dated schema identifier before
+publication (e.g. `2026-MM-DD`), matching OAI hosting convention.
+
+### Specification Extensions
+
+TODO: Decide whether `x-` prefixed extension fields are permitted on the
+Lifecycle Object, and document the pattern (field name pattern, reserved
+prefixes, allowed value types) if so.
+
+## Appendix A: Revision History
+
+| Version | Date | Notes |
+| ---- | ---- | ---- |
+| 1.0.0 | TBD | Initial release |