The poster known as
The phrase "the poster known as", abbreviated as TPKA, refers to a person posting messages under a nickname or pseudonym. It may be typed in front of the name as a way of identifying a poster whose name might not otherwise be recognized as referring to a specific person.
As an example, the sentence, "This article was typed by The playful mind," might not make sense to an unknowing reader, so it may be helpful to type instead This article was typed by TPKA The playful mind."
Other common methods of identifying a piece of text as a nickname include placing it in bold, italics, quotes, or otherwise formatting it differently from the main message.