[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: DTD Entity
Richard Knapp scripsit: > We are working on DTD with the following requirement: > > - Base element consists of Child elements First, Second, Third, and Fourth. > - First must appear under Base. > - Second, Third, and Fourth may appear zero or one time. > - Order is not important for elements Second, Third, and Fourth. (First, ((Second, ((Third, Fourth?) | (Fourth, Third?))?) | (Third, ((Second, Fourth?) | (Fourth, Second?))?) | (Fourth, ((Second, Third?) | (Third, Second?))?) )?) will do what you want. Yes, it's verbose, and it doubles in length every time you add a new optional element. But it works. That said, you should probably just impose a fixed order, and go with (First, Second?, Third?, Fourth?) BTW, Charles Reitzel's straight enumeration *is* non-deterministic, so it won't work.
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