IMO, Golden Arrow is only a nickname used by cyclists to facilitate identification of the group. All the official documentation that I've seen refers to it as Shimano 105. The nickname is based the symbol embossed onto the components and the colour of fill. If you look closely you will see that the symbol is actually a bow and arrow and may be homage to Archery, an early Shimano derailleur. I can't ever recall seeing any Shimano documentation refering to it as Golden Arrow. In fact, a lot of period Shimano advertisements actually print the bow and arrow symbol in blue, which would be a major marketing faux-pas if the official name was Golden Arrow.