An attribute declaration in a class, which takes the following form, declares one or more attributes of the class:
attribute Type AttributeDeclarator, ..., AttributeDeclarator;where the Type must be one of the following: int, float, boolean, String, Color, and Font
. An attribute declarator declares one attribute variable or an array of attribute variables of the Type. An attribute declarator for one single attribute variable has one of the following forms:
Identifier
Identifier in Domain
Identifier R expression
where Domain is an interval 
or a list of values 
, and R is an arithmetic relation symbol. The declarator Identifier in Domain is a domain constraint and Identifier R expression is an arithmetic constraint (see the Constraints Section). The declaration of component arrays will be described in the Arrays section.
The following shows three examples:
attribute int width == rect.width;
attribute Color color in {red,black,white};
attribute int x in 0..9;
The first one declares an attribute, named width, and constrains it
to be the same as rect.width where rect must be a component
declared in the same class. The other two examples declare two attribute variables and specify their domains.