Hidden bytes in chat messages

[Eruadarion]

I am looking for a good way to send data via chat to other players, but I don't want it to show as visible strings in the chat window. Only players that parse the chat with a Lua plugin should be able to read the bytes.

I remember there was a thread discussing sending chat messages with additional invisible costum data some time ago. It was an interesting read, but I don't remember the details. It was probably done by exploiting something like the <Select:IID> tags, or something similar. Unfortunately I am not able to find the discussion thread again. I thought it was in context of Thurallor's Blackboard plugin, but it seems like I am mistaken.

Can someone link me the original discussion?

Thanks!