Sign

Packet ID	Direction	Mojang Name	MCP Name
0x82	Both	SignUpdatePacket	Packet130UpdateSign

Both

Sent by the client when "Done" is clicked in the sign writing dialog.

Sent by the server when a sign is placed or loaded in.

Field	Type	Description
X	Integer	The X position of the sign
Y	Short	The Y position of the sign
Z	Integer	The Z position of the sign
Line 1	String16	The first line on the sign
Line 2	String16	The second line on the sign
Line 3	String16	The third line on the sign
Line 4	String16	The fourth line on the sign

Example Packet

Field	Value
X	70
Y	67
Z	-6015
Line 1	Hello!
Line 2	Thank you
Line 3	for reading
Line 4	this sign :D