# SubmapList.msg

## Overview

`SubmapList.msg` is a timestamped list of the submaps currently known to Cartographer. It is published periodically so that visualization and other consumers can track the state of the map.

## Fields

| Field | Type | Description |
| --- | --- | --- |
| `header` | `std_msgs/Header` | The standard ROS header. |
| `submap` | `cartographer_ros_msgs/SubmapEntry[]` | The array of submap entries. |

## Usage

- The `header.frame_id` is typically the map frame.
- Each element of `submap` follows the `SubmapEntry.msg` layout.
- Consumers compare `(trajectory_id, submap_index, submap_version)` triples between consecutive messages to detect new or updated submaps.