When mapping GSIM to our information model we got a bit confused about the difference between Code - CodeItem and Category - CategoryItem.

A CodeItem combines the meaing of the Category with a representation, like in "F-female", where female is the Category. What then is the code? "F"?

We have the same confusion for Category, above the Category is female, CategoryItem is defined as an element of a category set, would that not also be "female?

So my question is what is the difference between Category and CategoryItem and between Code and CodeItem?