The type of Chat app command. For details, see [Types of Chat app commands](https://developers.google.com/workspace/chat/commands#types).

| Enums ||
|---|---|
| `APP_COMMAND_TYPE_UNSPECIFIED` | Default value. Unspecified. |
| `SLASH_COMMAND` | A slash command. The user sends the command in a Chat message. |
| `QUICK_COMMAND` | A quick command. The user selects the command from the Chat menu in the message reply area. |
| `MESSAGE_ACTION` | A message action. The user selects the command from the message context menu in Chat. |