Spine Cards

[Pavey]

Hope i've posted this in the right place,please move if its wrong.

Anyway,call me stupid (a lot of people do),but what exactly are Spine Cards for/were for?
Obviously if you bend them you have a new spine, but on my Saturn games they always look shorter and wider than the regular CD case.And why would you need a new spine? (because your Spineless?)
Were they some sort of display system for Japanese shops,and why such a difference in price between games with and without spines.
Just wondering...

[Naiera]

They're used for placing ugly stuff such as barcodes on, instead of spoiling the box-art with it... They also make it much easier to see what format the game is for. On PCE CD/SCD games they don't really use any of the box-art/cover-art to pencil out that it's a PCE CD or SCD game, instead they use the spine for that.