Where's the key for "Copyboy"?

Note for younger readers: In the good old days of hot-metal printing, before computers were thought of, reporters in newsrooms used to shout COPY BOY! as soon as they had finished typing (sometimes handwriting) a story, for a messenger (copyboy) to take their work to a sub-editor, who would edit it before sending it to the printer. Many newspapers' best writers and top executives began work as copyboys.