Conref and generalization for constraint modules
When documents use different constraints, conref and generalization processors may examine the @domains to verify compatibility between the document instances.
Conref compatibility with constraints
To determine compatibility between two document instances, a conref processor can check the @domains attribute to confirm that
• The referencing document has a superset of the vocabulary modules in the referenced document.
• For each vocabulary module in the referenced document, the referencing document qualifies the common module with a subset of the constraints in the referenced document.
Some examples:
Referencing | Referenced | Resolution |
(topic) | (topic shortdescReq-c) | Allowed - content model of referenced topic is more constrained |
(topic shortdescReq-c) | (topic) | Prevented - content model of referenced topic is less constrained |
(topic hi-d) | (topic hi-d basicHighlight-c) | Allowed - domain extension list of referenced document type shell is more constrained |
(topic hi-d basicHighlight-c) | (topic hi-d) | Prevented - domain extension list of referenced document type shell is less constrained. |
(topic hi-d) | (topic noBasePhrase-c) (topic hi-d) | Allowed - referencing document type shell doesn't replace base element with domain extensions. |
(topic noBasePhrase-c) (topic hi-d) | (topic hi-d) | Prevented - referencing document type shell does replace base element with domain extensions. |
(topic task) (topic hi-d basicHighlight-c) | (topic simpleSection-c task simpleTaskSection-c) | Allowed - referencing shell has a subset of the constraints of the referenced shell on the common vocabulary modules. |
(topic shortdescReq-c task shortdescTaskReq-c) (topic hi-d basicHighlight-c) | (topic simpleSection-c task simpleTaskSection-c) | Prevented - referencing shell has constraints on common vocabulary modules that aren't in the referenced shell. |
Generalization and constraints
Similarly, to determine compatibility between a document instance and a target document type, a generalization processor can use the @domains and @class attributes for the document instance and the @domains attribute for the target document type to determine how to rename elements in the document instance. For each element instance, the generalization processor:
• Iterates over the @class attribute on the element instance from specific to general, inspecting the vocabulary modules.
• Looks for the first vocabulary module that is both present in the target document type and that has a subset of the constraints in the document instance.
If a module is found in the target document type, that module becomes the minimum threshhold for the generalization of contained element instances.
If a module is not found, the document instance cannot be generalized to the target document type and, instead, can only be generalized to a less constrained document type.
Note that a document instance can always be converted from a constrained document type to an unconstrained document type merely by switching the binding of the document instance to the less restricted schema (which would also have a different @domains attribute declaration). No renaming of elements is needed to remove constraints.
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