Clarify the documentation for parent change/commit.
Release-Notes: skip
Change-Id: I88fa2cb496fa99af2dcda38feccdd06b95ed06aa
diff --git a/Documentation/rest-api-changes.txt b/Documentation/rest-api-changes.txt
index 65275bd..2f144c6 100644
--- a/Documentation/rest-api-changes.txt
+++ b/Documentation/rest-api-changes.txt
@@ -7216,11 +7216,16 @@
Whether the new change should be set to work in progress.
|`base_change` |optional|
A link:#change-id[\{change-id\}] that identifies the base change for a create
-change operation. Mutually exclusive with `base_commit`.
+change operation. +
+Mutually exclusive with `base_commit`. +
+If neither `base_commit` nor `base_change` are set, the target branch tip will
+be used as the parent commit.
|`base_commit` |optional|
A 40-digit hex SHA-1 of the commit which will be the parent commit of the newly
-created change. If set, it must be a merged commit on the destination branch.
-Mutually exclusive with `base_change`.
+created change. If set, it must be a merged commit on the destination branch. +
+Mutually exclusive with `base_change`. +
+If neither `base_commit` nor `base_change` are set, the target branch tip will
+be used as the parent commit.
|`new_branch` |optional, default to `false`|
Allow creating a new branch when set to `true`. Using this option is
only possible for non-merge commits (if the `merge` field is not set).
