The parameters for Broadcast are:

Name Type Default Values Description
style string none error, warning, info the style of the message
title string - - the title of the message
body string - - the body of the message
displayTime (optional) string number of seconds the message to be shown - number of seconds
requireInteraction string false true,false You can use this property if you require a user to interact with the Broadcast if it is at the start of the flow
disableInteraction string false true,false If enabled, messenger will not send up any interaction to the bot

If no displayTime is provided the Broadcast message will be closeable (a small ‘x’ in the top right corner)

An example of Broadcast Markup is: