Origin of briefcasebrief, document + case2.
briefcase - Computer Definition
In Windows 95/98, a system folder used for synchronizing files between two computers, typically a desktop and laptop computer. Files to be worked on are placed into a Briefcase, which is then transferred to the second machine via floppy, cable or network. The Briefcase is then brought back to the original machine after its contents have been edited on the second machine, and a special update function replaces the original files with the new ones.