In this post I will demostrate the usage of cisco cables SFP-H10GB-CU3M enlew of SFPs for connecting a FML to a cisco 6509-E.
Most if not ALL Fortinet gear, is pretty much cisco compatible for ALL SFPs that I've used in the past. You can pretty much use any standard badged/labeled cisco SFPs in fortunate gear and it will work.
Here's the FML 3KD configuration for the SFP slot interface in the back.
No on the switch I was surprised that cisco showed there own cables not compatible .
NOTE: I'm using the service unsupported transceiver commands on this switch btw.