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> a paragraph cannot appear nested
> within another paragraph unless
> there is an intervening table, which is in
> my book a structural rule
Awesome example!
So "structural rules" are those that specify constraints on the structure of XML instances? That is, they specify what elements and attributes can go where.
Here's a rule that has nothing to do with the structure of XML instances:
The meeting start-time must be before the end-time.
Therefore, this is a business rule and should not be expressed in XML Schema using the <assert> element, correct?
Another example,
The total-amount-due for an order is
computed as the sum of the line-item
amount(s) for the order plus tax.
Again, this has nothing to do with the structure of XML instances and therefore is a business rule and should not be expressed in XML Schema using the <assert> element, correct?
Let me summarize what I've learned:
1. Use the <assert> element only to express structural rules.
2. Structural rules are those that specify constraints on the structure of XML instances; that is, what elements and attributes can go where.
3. All other rules (non-structural rules) are business rules and should be not expressed in XML Schema using the <assert> element.
Do you agree?
/Roger
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