In addition to code 128, please try to follow the standard set out in EAN-128, which prescribes an international standard for each composite (as in your case) bar code. It goes like this.
(xx)XXXXXXXXXXXXXXXXXXX(yyy)YYYYYYYYYYYYYYYYYY and so on.
The small letters (within parentheses) are the standard business codes (eg:xx=ProductIdentifier) and XXXXXX - the value of xx.
This is internationally accepted (and if in the USA, the sunrise date for merging UPC with EAN is Jan 2005 - I think).
I don't have the list of EAN codes right now, but I believe google will get it for you.
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