# Composition objects

> Reusable objects used inside blocks and elements.

Composition objects define text, options, confirmation dialogs and other pieces shared by many blocks and elements.

| Name | Summary |
|---|---|
| [Attachment object](https://workstation.repzo.com/docs/developers/block-kit/objects/attachment-object) | Slack's legacy secondary attachment: content in a box with a coloured bar down its side, sent in a message's `attachments` array next to (or instead of) `blocks`. |
| [Confirmation dialog object](https://workstation.repzo.com/docs/developers/block-kit/objects/confirmation-dialog-object) | Adds a confirmation step to an interactive element: before the action reaches your app, the reader sees a dialog and must confirm it. |
| [Conversation filter object](https://workstation.repzo.com/docs/developers/block-kit/objects/conversation-filter-object) | Limits which conversations a conversations select menu or conversations multi-select menu offers. |
| [Dispatch action configuration object](https://workstation.repzo.com/docs/developers/block-kit/objects/dispatch-action-configuration-object) | Defines when a text input element sends a `block_actions` interaction payload while the reader is still typing. |
| [Option group object](https://workstation.repzo.com/docs/developers/block-kit/objects/option-group-object) | Groups option objects under a heading in a select menu or multi-select menu. |
| [Option object](https://workstation.repzo.com/docs/developers/block-kit/objects/option-object) | A single item in a select menu, multi-select menu, checkbox group, radio button group or overflow menu. |
| [Text object](https://workstation.repzo.com/docs/developers/block-kit/objects/text-object) | Defines text for blocks and elements, either as plain text or formatted with `mrkdwn`. |
| [Trigger object](https://workstation.repzo.com/docs/developers/block-kit/objects/trigger-object) | Defines the trigger a workflow button points at, and the input parameters to start it with. |
| [Workflow object](https://workstation.repzo.com/docs/developers/block-kit/objects/workflow-object) | Defines the workflow a workflow button starts. |