From the old wiki:
The typing notification is similar to Jabber’s “Chat State Notifications” .
This extension adds the new command type TPN. If client supports this it must add TYPE in INF SU field.
TPN should be send to Reply-To user (for chatroom orgainzation and etc) (PM flag in MSG if any). In that case chatrooms bot can normally broadcast this messages to “joined” users.
Contexts: F, T
00 - gone (closed tab, minimised window, etc…)
01 - inactive (changed tab, window became unfocused (but not closed/minimised), etc)
02 - paused (paused typing)
10 - active (now in this tab, reading message, actively participating in the chat session)
11 - composing (now typing a message)
All TPN messages are sent when event occurs. 00, 01, 02 - client should send; 10, 11 - client must send.
Added to ADC-Ext 1.0.6.