Attribute generalization

Attributes specialized from props or base can be generalized using a special attribute generalization syntax. Specialization-aware processes should be able to recognize and process both the specialized and generalized forms of an attribute as being equivalent in their values.

When generalized, specialized attribute values are added to the end of their target ancestor attribute, within parentheses preceded by the name of the specialized attribute. For each attribute that has been generalized, a separate label and parentheses-enclosed set of values is added to the ancestor attribute.

For example, given that "jobrole" is an attribute specialized from "person", which in turn is specialized from "props":

jobrole="programmer" can be generalized to person="jobrole(programmer)" or to props="jobrole(programmer)"
props="jobrole(programmer)" can be respecialized to person="jobrole(programmer)" or to jobrole="programmer"

Generalization and respecialization can use the domains attribute to determine the ancestry of role, and therefore the validity of person as an intermediate target for generalization.

Generalized attributes are typically not expected to be authored or edited directly, but to preserve the values of the specialized attributes while the document is temporarily in a generalized form.

If a single element contains values for an attribute in more than one syntax, that is an error. For example <p person="role(programmer)" role="admin">...</p> both provide values for the role attribute, but one in a generalized syntax and one in a specialized syntax. This is an error condition, since it means the document has been only partially generalized, or has been generalized and then edited using a specialized document type.