As far as the `Create` activity is concerned, only `Note` is a first-class citizen in Mastodon, because Mastodon is a microblogging engine. For other types of supported objects, Mastodon internally creates a toot representation, for example, an `Article` becomes a toot with the `title` and `url` of the original object, as users are expected to navigate to the original URL to read the article with rich text formatting. For `Image` and `Video` objects, the `title` is likewise used to fill the content of the toot, with the original file attached to the toot.
The `Flag` activity allows reporting content on another server, and its `object` can be either one or more actors, or one or more objects attributed to various actors. The `Add` and `Remove` activities only work with [featured collections](#featured-collection). The `Delete` activity can be used to delete all local data of the sender when the `object` of it is the sender. The `Update` activity can only be used to update the profile of the sender. Likewise, the `Move` activity allows re-assigning followers from the sender (`object`) to another actor (`target`), but only if the other actor references the sender in the `alsoKnownAs` property.
What is known in Mastodon as "pinned toots", or statuses that are always featured at the top of people's profiles, is implemented using an extra property `featured` on the actor object that points to a `Collection` of objects. Example:
Mastodon supports arbitrary emojis, that is, small images uploaded by admins and invokable via shortcodes. For this, an `Emoji` type is used. These emojis are listed in the `tag` property just like `Mention` and `Hashtag` objects, since they are entities that affect how the text is rendered. Example:
```json
{
"@context": [
"https://www.w3.org/ns/activitystreams",
{
"toot": "http://joinmastodon.org/ns#",
"Emoji": "toot:Emoji"
}
],
"id": "https://example.com/@alice/hello-world",
"type": "Note",
"content": "Hello world :Kappa:",
"tag": [
{
"id": "https://example.com/emoji/123",
"type": "Emoji",
"name": ":Kappa:",
"icon": {
"type": "Image",
"mediaType": "image/png",
"url": "https://example.com/files/kappa.png"
}
}
]
}
```
### Focal points
Mastodon supports setting a focal point on uploaded images, so that wherever that image is displayed, the focal point stays in view. This is implemented using an extra property `focalPoint` on the `Image` objects. The property is simply an array of two floating points between 0 and 1. Example:
