National Puzzlers' League
The National Puzzlers' League, established in 1883, is an organization dedicated to puzzling, particularly wordplay and word games. Members often take on pseudonyms known as "noms", which often involve puns and wordplay. The league publishes a monthly magazine known as The Enigma. Every year (typically in July), the league also organizes the NPL Convention.
NPL puzzles are classified into several categories, including "flats", which have one-line answers and often are written in the form of a poem, and "forms" which are multi-line answers, such as a word square or other geometric shapes. There is an extensive guide to the shorthand used to denote the types of flats and forms seen in The Enigma.