XSD 1.1: Attribute is supposed to only have values of another attribute
问题 For a card-game that I am supposed to design, I have the task of implementing an attribute that can only have values that two other attributes can have. I already asked a question close to this one, where I was able to restrict that attribute to have the same value as another attribute. However, when it has not the same value, the compiler is giving an error message. Background: I have the element "card" which is divided into the element "type" (which also defines a "color" as an attribute)