Aircraft type and code

I file IFR IACO format all the time. In my flight plan it will list my aircraft type as BE33A/L . At first I thought I must have filled out the equipment list wrong because I do not have Loran. But, the equipment list is right and loran is not checked. So I checked into this and found out that the /letter codes in the IACO flight plan are not the same as in a domestic IFR plan. So, for example, my aircraft would be BE33A/G on the domestic IFR filing but not the IACO. So, after lots of verification, I am ok with it.
Here is what adds to my confusion. Why do some of my flight plans in the history of flights for my aircraft show the type as BE33A/G anyway and on some flights, all filed IFR w/IACO, the type is listed as BE33A/R? Does this have something to do with how ATC ultimately puts you into the system once the flight plan is actually activated? For example via vectors vs. as filed?, direct vs waypoints?

I know a couple of flight instructors confused by this too. So a little help would be appreciated.