Epson Stylus Pro 7700 Series Reference Manual page 11

Roll Media Length Tracking and Identification System
Automatic Bar Code Tracking System
Realtime Automatic Remaining Roll Media Length Counter
Auto Bar Code Printing of Remaining Roll Media Information for Faster Reloading
Adjustable Roll Media Length Setting to Compensate for Various Roll Lengths
Very Useful for Tracking Partially Used Media Rolls
Auto Roll Media Identification – Both Genuine Epson and Custom Media Setting(s)
Can Be Disabled if Not Required by Your Workflow
Example Bar Code Tag Printed on the Edge of Media