Required and optional data

Sometimes, a certain data object is optional; it does not have to be present in the data. For example, in purchase order data, there might be a billing address and a shipping address. If the company wants the items shipped to the billing address, the shipping address would not appear in the data. The shipping address would be optional; it might not appear in the data.

Another example is a middle name field. Some people do not have a middle name, so the middle name field might be optional.

The schema designer needs to know what data is optional. This is evident from the component range. The range minimum tells how many occurrences of that object must be present in the data. These are the required occurrences. Optional occurrences are the ones that are not required.

DateField (0:1)

DateField (1:5)

The range is between one and five occurrences. This means that one occurrence of DateField is required and the remaining four occurrences are optional.

The following table lists examples of components and explanations of their status.