Jeez man. ( A Canadianism.) You are ancient and practically a Canuck.
This usage of coop is probably exclusively Canadian. We designed university programs so that students spent alternating semesters studying and working in the field. The students were called coops. An approximate current synonym is interns, except that coops were paid and interns are not. I don't know whether this system is still operating.
@ keannu: When you admit to knowing cobol you confess to being very ancient. Don't take it badly. I wrote cobol too