Understanding Model Number

So I have used the Google machine to identify that my E25RWETE is a

E: Evinrude
25: 25 HP
RW: Commercial with Interlock
ET: 1993
--- Due to a lack of a L, Y, X or Z I believe it is short/standard shaft
E: I think this doesn't actually identify anything in particular

So someone correct me if I'm wrong.

But my questions are:
A - What does "Commercial" and or "with Interlock" mean? It is a rope start, but I don't know what more to make of this.
B - I've seen that a standard shaft is 15", but I measured it out to 18". Unless I either mismeasured, or it has something to do with the "Commercial" aspect.

I would appreciate the help. Thanks!

I believe you are measuring wrong.------I would say your motor fits properly on a 15" transom----Sometimes " commercial " motors have slightly different features.---Or are a way of getting rid of older technology left over inventory !----Any pictures of your motor ?

There's the photo.
I'm most confused by the "Interlock"

" interlock " ----means that if it is gear you can not pull the recoil starter.------Simple linkages with a cable.------Unlocking it with your smartphone is not coming out for another 5 years I think.