There is a particular syntax to generalize attributes that have been specialized from
the @props or @base attribute. Specialization-aware processors should be able
to recognize and process both the specialized and generalized forms of an attribute
as being
equivalent in their values.
When a specialized attribute is generalized to an ancestor attribute, the value of
the
ancestor attribute consists of the name of the specialized attribute followed by its
specialized value in parentheses. 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"
In this example, generalization and respecialization can use the @domains attribute
to
determine the ancestry of the specialized @jobrole attribute, and therefore the validity
of
the specialized @person attribute as an intermediate target for generalization.
If more than one attribute is generalized, the value of each is separately represented
in
this way in the value of the ancestor attribute.
Generalized attributes are typically not expected to be authored or edited directly,
but are
used by generalizing processors to preserve the values of the specialized attributes
during
the time or in the circumstances in which the document is in a generalized form.
A single element
may not contain both generalized and specialized values
for the same attribute. For example, this element:
<p person="jobrole(programmer)" jobrole="admin">...</p>
provides
two values for the @jobrole attribute, but one is in a generalized syntax and the
other 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.
