The user is preparing a message; typing, recording, uploading, etc. This update is valid for 6 seconds. If no repeated update received after 6 seconds, it should be considered that the user stopped doing whatever he's been doing.
updateUserTyping#5c486927 user_id:int action:SendMessageAction = Update;
Param added in Layer 17.
Below you will find information on scheme changes. For more details on the use of layers, see Invoking API methods.