What is meant by iTunes Barcode?
Barcodes for iTunes are general use UPC barcodes not different from other products.
iTunes requires that all albums have a UPC and all individual songs have an ISRC. ISRC codes are a simple, internationally recognized numbering system for audio and music video recordings. The ISRC, in addition to tracking for Billboard charting, also allows you to get paid for digital music sales by ensuring that your royalties are tracked properly (particularly important for iTunes).
Source - http://simplybarcodes.net/barcode-itune.html