Please help about ifindex issue

Please help about ifindex issue

Dear Netflow Analyzer,

I'm using Netflow analyzer application for reporting IN and OUT traffic. 
So, i can't understand  what related to between Interface name (ifindex) on Netflow Analyzer and Fortigate 200B (OS 5.2.x) is.

For ex: Based on pictures under attach files, you could show me that with an ifindex15 on Netflow analyzer, so what is interface (name or index) on Fortigate?

Please find the attach file for detail and tell me some good information.

Thank you.

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