Writing a DTD: How to achieve this children setup
- by Boldewyn
The element tasklist may contain at most one title and at most one description, additionally any number (incl. 0) task elements in any order.
The naive approach is not applicable, since the order should not matter:
<!ELEMENT tasklist (title?, description?, task*) >
Alternatively, I could explicitly name all possible options:
(title, description?, task*) |
(title, task+, description?, task*) |
(task+, title, task*, description?, task*) |
(description, title?, task*) |
(description, task+, title?, task*) |
(task+, description, task*, title?, task*) |
(task*)
but then it's quite easy to write a non-deterministic rule, and furthermore it looks like the direct path to darkest madness. Any ideas, how this could be done more elegantly?
And no, an XSD or RelaxNG is no option. I need a plain, old DTD.
