[tryton] Product attributes: String

[Axel Braun]

Hi,

I want to add a product attribute, and create and 'attribute set'
Name (of the attribute): Clear (e.g. Color)
Type (like Char): clear
String: Is this a fixed value for the attribute? (e.g. Yellow)
How do I define the string if a set of values is possible? Can this set of 
values be extended by the user?

Thx
Axel