When reading Programmers at Work (by Susan Lammers), they often refer to code as "listings". Why is that?
The term dates back to a time when programs were stored on eighty-column Hollerith-encoded punch cards. I am old enough to remember those days. All of my early programs where entered via a keypunch machine and debugged via printed compiler output "listings."
As an aside: early terminals were eighty columns wide because that line size mapped well to "card image" data. Most of the early on-line systems were merely data collection and presentation subsystems for card-image batch systems. This information processing model was known as "deferred batch."
It refers to printed out code.
Actually, in a food manufacturer that I've been to in the last few years, they still print out all code from their PLC's and keep them in hanging files. Part of the procedure for updating a program always involves updating the paper copies.
Maintenance people regularly come in and pull a binder to look at it. In some ways it's handy, especially when you can look at it on big plots (it's a graphical programming language) rather than on a tiny screen.