diff --git a/versions/1.1.md b/versions/1.1.md
index c8e03ce..f2ca812 100644
--- a/versions/1.1.md
+++ b/versions/1.1.md
@@ -435,6 +435,36 @@ A guard compares a keyed [aggregate](#aggregates--keyed-cross-entity-totals) aga
 
 `immutableWhen` requires a `function: EntityStatus` relation; `immutable: true` needs none and is mutually exclusive with it. System / workflow writes stay possible — corrections to an immutable record are flow-generated reversals, never edits.
 
+### locksWithMaster — a child collection that outlives its master's lock
+
+An entity's immutability covers **that entity**. A composition child is a different entity, so a
+master that locks says nothing about whether its child collections should:
+
+```yaml
+- name: Invoice
+  immutableWhen: "Status == 3"        # ISSUED: the document's own content freezes
+- name: InvoiceAllocation
+  locksWithMaster: false              # ...but money keeps being recorded against it
+  relations:
+    - { name: Invoice, kind: manyToOne, to: Invoice, composition: true, required: true }
+```
+
+The canonical case is settlement: an issued invoice's lines are frozen — that is the audit trail —
+while payment allocations against it go on being recorded for months. Content and settlement are
+different lifecycles on the same document.
+
+> **Normative.**
+> `locksWithMaster` defaults to **true**, so a child that says nothing keeps freezing with its
+> master.
+> A generator MUST NOT extend a master's user-write immutability to a child collection declared
+> `locksWithMaster: false` — including the affordances it renders for that collection, not merely
+> the writes it accepts. A read-only rendering that the server would have permitted is the same
+> defect as a refused write.
+> The declaration is only meaningful on a composition child whose master actually declares
+> immutability; a generator MUST reject it elsewhere rather than ignore it, since an inert
+> declaration is indistinguishable from a working one until someone needs it.
+> It does not apply to a document's own line items, which ARE the document's content.
+
 ### hierarchy / leafOnly — tree entities
 
 ```yaml
@@ -1366,6 +1396,7 @@ One line per construct, linking into the chapters above.
 | [`number`](#document-numbering) | a platform-numbered, gap-free document field |
 | [`checks`](#checks--declarative-validations) | cross-field / cross-line validations |
 | [`immutableWhen` / `immutable`](#immutablewhen--immutable--user-write-immutability) | reject user writes in a status / append-only |
+| [`locksWithMaster`](#lockswithmaster--a-child-collection-that-outlives-its-masters-lock) | a child collection that stays writable while its master is locked |
 | [`hierarchy` / `leafOnly`](#hierarchy--leafonly--tree-entities) | tree entities, leaf-only references |
 | [calculated fields](#calculated-fields) | server + UI-evaluated expressions, date helpers, call-outs |
 | [`relations` / `composition`](#relations) | associations and master-detail compositions |