I know about the Radio Frequency Interference, but I don't think that's it.
The context is in which PCM is which. I am hunting a PCM for a 95 2500 Auto, and there are several PCMs. I found one that is for an "RFI" , but I don't know what it means, and how it will affect my truck, which I don't think is an RFI, based on the PCM that came out of it.
Below is the table of flash info I found with this reference. I have also seen the reference for gas engines.
95 5.9 BR DIESEL AUTO
95 5.9 BR DIESEL AUTO RFI
95 5.9 BR FEDERAL AUTO RFI

The original table, but the forum strips the formatting so it's hard to read.
Calibration Type Old PN New PN TSBs
95 5.9 BR DIESEL AUTO PCM 56028335 04856080 21-04-95
95 5.9 BR DIESEL AUTO RFI PCM 56028336 04798745 21-04-95
95 5.9 BR FEDERAL AUTO RFI PCM 56028326 04797174 18-11-95

I am trying to figure out if a 56028336 PCM will work in my truck, which is a 56028335.

Thanks,
Chris

 

Just a guess here but I think it means PCM has built in RFI capability. Which means it has built in filter to reject RFI interference from fuel pump, alternator, wiper motor, etc.