The Bar Code FAQ [L1 ] has valuable information, but is available only in PDF. BarCode1 FAQ [L2 ] is an entirely different document.
ZZZ [L3 ] is a point-of-sale application coded in Tcl.
Archiver [L4 ] is an archival application written in Tcl.
One CueCat decoder [L5 ] is written in Tcl.
"A fully automated high-throughput HPLC-MS system ..." is an academic article which describes a Tcl-coded biochemical system which employs barcodes.