International Alliance of Theatrical Stage Employees. Often abbreviated "IA", the full name is The International Alliance of Theatrical Stage Employees, Moving Picture Technicians, Artists and Allied Crafts of the United States, Its Territories and Canada.
Since its jurisdiction is divided into smaller geographic districts, the "Local Stagehand Union" is often shortened to "the Local" or "the Union". New York City is Local#1, Chicago is Local#2. Cleveland is #27. The higher the number, the younger the local. Las Vegas is Local #720.
In 1999, IATSE absorbed USAA, United Scenic Artists of America (which had three locals: NYC #829, Chicago #350, and Los Angeles #?), which became IATSE Local #829, thus allowing one union to represent designers as well as technicians.
The five-sided, iron-cross type, logo is often called "the bug" and in certain Union houses, all scenery must have the logo displayed on the back side. The circular USAA logo is to be found on on all drawings issued by a designer working under a union contract.