Using DTD can I specify an exact number of element occurrences?

问题

I am trying to do this exercise in XML and I am stuck at this particular point. I am being asked to create a DTD that will satisfy a list of requirements and I cannot find a way to achieve the following:

The seasonal_prices' list can have none, one, two or three occurrences of the 'season_price' element

Is there a way to achieve this using only a DTD?

回答1:

Is there a way to achieve this using only a DTD?

Nope.

You can only do:

• season_price (exactly one)
• season_price? (zero or one)
• season_price+ (one or more)
• season_price* (zero or more)

See https://www.w3.org/TR/xml11/#sec-element-content for more info.

----- Edit -----

Like you mentioned in another question, you could do this using ? like:

<!ELEMENT seasonal_prices (season_price?, season_price?, season_price?)>

but there's no direct way like in XML Schema (minOccurs/maxOccurs).

来源：https://stackoverflow.com/questions/61272296/using-only-a-dtd-are-there-any-disadvantages-in-limiting-the-number-of-children