> ## Documentation Index
> Fetch the complete documentation index at: https://www.plain.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Manage the navigation

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The help center index defines the order in which article groups and articles appear in the help center navigation, as well as the parent-child relationships between them.

`updateHelpCenterIndex` replaces the entire navigation tree in a single call. To avoid clobbering concurrent edits, you must include the `hash` returned by the previous `helpCenterIndex` query — if the help center has been re-indexed since you read it, the call will fail and you should re-fetch the latest index and re-apply your changes.

Each entry references an existing article or article group by ID, and optionally a parent group ID to nest it within a group.

The `type` field accepts:

* `ARTICLE` — references an existing help center article by its `entityId`. The displayed title is taken from the article itself.
* `ARTICLE_GROUP` — references an existing article group by its `entityId`. The displayed title is taken from the group itself.
* `HEADING` — an inline section title that groups the items beneath it in the sidebar. Headings have no backing entity, so you supply your own unique `entityId` (any opaque string, conventionally prefixed `hch_`) and a non-empty `title`. The `title` field is ignored for `ARTICLE` and `ARTICLE_GROUP` items.

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