This term and topic seems to give null search results, so here's a quick timesaver for where to get explanation & details...
- pipe trick
- pipe link
- w:Help:Piped_link#Piped_link - the mysterious piped link, a term I hadn't heard nor recall seeing in 10 years contributing on nine WikiMedia projects. (To my chagrin, this was what I called a pipe trick! Ooops!)