Fair Isle or not, that is the question

A great confusion in the world 

about the use of the term 

Fair Isle

I am a Norwegian knitter (like my mother and grand mother) living in Pennsylvania for the time being.
Through the years I have done a lot of color-work knitting and followed mostly Norwegian patterns.

Internet has changed our access to the outer world and what is happening out there. We gain knowledge about new ideas and inspiration within a blink of an eye. The online knitting community Ravelry has come to mean a lot to me and now I see to 4 million other members.

The term "Fair Isle" is now floating around anywhere to-stranded knitting appears and has come to mean simply color-work. I have even seen typically Norwegian Sweaters called Fair Isle on Pinterest. From the search engine and various peoples blogs I had  hoped to find help to distinguish Fair Isle from other knitting styles, to really pin down the difference here and find a definition. The book with the "200 Fair Isle Motifs" has helped me a long way, but I wonder about  what is really the traditional Fair Isle knitting that separates it from the other color-work styles.

The Mystery

In some sweaters I have seen thees borders separated with a single row in contrast color. In some others I have seen the background color just continue "alone for 2 rows before the next border starts with 2 borders in a different background color and without a separating "line".
Other places I have found two colors meet and every other is knit in each color as a transition to the next pattern band/border.

Otherwise we are suddenly in England and knitting in large patterns and color-work that float all over and I think we have left the Fair Isle altogether. Sometimes I see that same style in Norwegian patterns, like with Solveig Hisdal were she studies old fabric from folk museums and transfer them into  large pattern work over the whole garment.

I really wanted to make my own true Fair Isle this time. In order to do that the distinct caracter of the Fair isle sweater must first be pin-pointed.

But the question remains, will that be possible?