Ledger formats: improve landing page, etc.

content/_snippets/macros/page-children.md

@@ -0,0 +1,16 @@
+{% macro page_children(pg, depth, max_depth, show_blurbs) %}
+{% if pg.children %}
+{% if depth == 1 %}<ul class="children-display">{% endif %}
+  {% for child in pg.children %}
+<li class="level-{{depth}}"><a href="{{child.html}}">{{child.name}}</a>
+  {% if child.status == "not_enabled" %}:not_enabled:{% endif %}
+  <p class="blurb child-blurb">{{child.blurb}}</p>
+</li>
+  {% if child.children and depth < max_depth %}
+{{ page_children(child, depth+1, max_depth, show_blurbs) }}
+  {% endif %}
+  {% endfor %}
+
+{% if depth == 1 %}</ul><!--/.children-display-->{% endif %}
+{% endif %}
+{% endmacro %}

content/_snippets/rippled-api-links.md

@@ -21,7 +21,7 @@
 [Ledger Index]: basic-data-types.html#ledger-index
 [ledger index]: basic-data-types.html#ledger-index
 [レジャーインデックス]: basic-data-types.html#レジャーインデックス
-[ledger format]: ledger-data-formats.html
+[ledger format]: ledger-object-types.html
 [レジャーフォーマット]: ledger-data-formats.html
 [Marker]: markers-and-pagination.html
 [マーカー]: markers-and-pagination.html

content/references/rippled-api/ledger-data-formats/ledger-data-formats.md

@@ -0,0 +1,24 @@
+---
+html: ledger-data-formats.html
+funnel: Build
+doc_type: References
+supercategory: rippled API
+category: Ledger Data Formats
+blurb: Learn about individual data objects that comprise the XRP Ledger's shared state.
+---
+# Ledger Data Formats
+
+Each [ledger version](ledgers.html) in the XRP Ledger is made up of three parts:
+
+- **[Ledger Header](ledger-header.html)**: Metadata about this ledger version itself.
+- **[Transaction Set](transaction-formats.html)**: All the transactions that were executed to create this ledger version.
+- **[State Data](ledger-object-types.html)**: The complete record of objects representing accounts, settings, and balances as of this ledger version. (This is also called the "account state".)
+
+## State Data
+
+The ledger's state data consists of objects, or _ledger entries_, stored in a trie format. To store or retrieve an object in the state data, the protocol uses that object's unique **[Ledger Object ID](ledger-object-ids.html)**.
+
+A ledger object's data fields depend on the type of object; the XRP Ledger supports the following types:
+
+{% from '_snippets/macros/page-children.md' import page_children with context %}
+{{ page_children(pages|selectattr("html", "eq", "ledger-object-types.html")|first, 1, 1, True) }}

content/references/rippled-api/ledger-data-formats/ledger-header.md

@@ -1,7 +1,7 @@
 # Ledger Header
 [[Source]](https://github.com/ripple/rippled/blob/master/src/ripple/ledger/ReadView.h#L71 "Source")
 
-Every ledger version has a unique header that describes the contents. You can look up a ledger's header information with the [ledger method][]. The contents of the ledger header are as follows:
+Every [ledger version](ledger-data-formats.html) has a unique header that describes the contents. You can look up a ledger's header information with the [ledger method][]. The contents of the ledger header are as follows:
 
 | Field                        | JSON Type | [Internal Type][] | Description   |
 |:-----------------------------|:----------|:------------------|:--------------|

content/references/rippled-api/ledger-data-formats/ledger-object-ids.md

@@ -1,7 +1,11 @@
 # Ledger Object IDs
 <a id="sha512half"></a>
 
-All objects in a ledger's state tree have a unique ID. This field is returned as the `index` field in JSON, at the same level as the object's contents. The ID is derived by hashing important contents of the object, along with a [namespace identifier](https://github.com/ripple/rippled/blob/master/src/ripple/protocol/LedgerFormats.h#L99). The [ledger object type](ledger-object-types.html) determines which namespace identifier to use and which contents to include in the hash. This ensures every ID is unique. To calculate the hash, `rippled` uses SHA-512 and then truncates the result to the first 256 bits. This algorithm, informally called **SHA-512Half**, provides an output that has comparable security to SHA-256, but runs faster on 64-bit processors.
+Each [object in a ledger's state data](ledger-object-types.html) has a unique ID. The ID is derived by hashing important contents of the object, along with a [namespace identifier](https://github.com/ripple/rippled/blob/master/src/ripple/protocol/LedgerFormats.h#L99). The [ledger object type](ledger-object-types.html) determines which namespace identifier to use and which contents to include in the hash. This ensures every ID is unique. To calculate the hash, `rippled` uses SHA-512 and then truncates the result to the first 256 bits. This algorithm, informally called **SHA-512Half**, provides an output that has comparable security to SHA-256, but runs faster on 64-bit processors.
+
+Generally, a ledger object's ID is returned as the `index` field in JSON, at the same level as the object's contents. In [transaction metadata](transaction-metadata.html), the ledger object's ID in JSON is `LedgerIndex`.
+
+**Tip:** The `index` or `LedgerIndex` field of an object in the ledger is the ledger object ID. This is not the same as a [ledger index][].
 
 ![Diagram: rippled uses SHA-512Half to generate IDs for ledger objects. The space key prevents IDs for different object types from colliding.](img/ledger-indexes.png)
 

content/references/rippled-api/ledger-data-formats/ledger-object-types/negativeunl.md

@@ -6,6 +6,7 @@ supercategory: rippled API
 category: Ledger Data Formats
 subcategory: Ledger Object Types
 status: not_enabled
+parent: ledger-object-types.html
 blurb: List of validators currently believed to be offline.
 ---
 # NegativeUNL