That would make no sense, so If I asked for a fan fret with a saddle spacing of my favourite string spacing of 16.5mm, I would actually have a physical string spacing of 13.75mm. That would be a bit tight (although still prefereable to 21mm on the ibanez).
Not sure what you mean about string guages, that has no relevance to string spacing, the sadles are in the same place whether you put strings on or not.
Just in case we are talking at cross purposes, this is the Ibanez. I would call this 17.5mm spacing (as do ibanez), its 21mm between saddles