The following values are represented:
1 – Msi scanner
2 – Inventory rule
4 – File list
8 – Add Remove programs entry
16 – Patch
32 – Server
64 – “Software Catalog Data Provider” using the rules provided by PC-Ware
"What does the Source number indicate for Software Components, including referenced in Installed Software?"
http://www.symantec.com/docs/HOWTO84082