Real World XML (2nd Edition)
| It is actually possible to specify that an element can contain both PCDATA and other elements. Such a content model is called mixed. To specify a mixed-content model, just list #PCDATA along with the child elements you want to allow: Listing ch03_05.xml
<?xml version = "1.0" standalone="yes"?> <!DOCTYPE DOCUMENT [ <!ELEMENT DOCUMENT (CUSTOMER)*> <!ELEMENT CUSTOMER (NAME,DATE,ORDERS)> <!ELEMENT NAME (LAST_NAME,FIRST_NAME)> <!ELEMENT LAST_NAME (#PCDATA)> <!ELEMENT FIRST_NAME (#PCDATA)> <!ELEMENT DATE (#PCDATA)> <!ELEMENT ORDERS (ITEM)*> <!ELEMENT ITEM (PRODUCT, NUMBER, PRICE)> <!ELEMENT PRODUCT (#PCDATA PRODUCT_ID)*> <!ELEMENT NUMBER (#PCDATA)> <!ELEMENT PRICE (#PCDATA)> <!ELEMENT PRODUCT_ID (#PCDATA)> ]> <DOCUMENT> <CUSTOMER> <NAME> <LAST_NAME>Smith</LAST_NAME> <FIRST_NAME>Sam</FIRST_NAME> </NAME> <DATE>October 15, 2003</DATE> <ORDERS> <ITEM> <PRODUCT>Tomatoes</PRODUCT> <NUMBER>8</NUMBER> <PRICE>.25</PRICE> </ITEM> <ITEM> <PRODUCT> <PRODUCT_ID> 124829548702121 </PRODUCT_ID> </PRODUCT> <NUMBER>24</NUMBER> <PRICE>.98</PRICE> </ITEM> </ORDERS> </CUSTOMER> <CUSTOMER> <NAME> <LAST_NAME>Jones</LAST_NAME> <FIRST_NAME>Polly</FIRST_NAME> </NAME> <DATE>October 20, 2003</DATE> <ORDERS> <ITEM> <PRODUCT>Bread</PRODUCT> <NUMBER>12</NUMBER> <PRICE>.95</PRICE> </ITEM> <ITEM> <PRODUCT>Apples</PRODUCT> <NUMBER>6</NUMBER> <PRICE>.50</PRICE> </ITEM> </ORDERS> </CUSTOMER> <CUSTOMER> <NAME> <LAST_NAME>Weber</LAST_NAME> <FIRST_NAME>Bill</FIRST_NAME> </NAME> <DATE>October 25, 2003</DATE> <ORDERS> <ITEM> <PRODUCT>Asparagus</PRODUCT> <NUMBER>12</NUMBER> <PRICE>.95</PRICE> </ITEM> <ITEM> <PRODUCT>Lettuce</PRODUCT> <NUMBER>6</NUMBER> <PRICE>.50</PRICE> </ITEM> </ORDERS> </CUSTOMER> </DOCUMENT> However, there is a big drawback to using the mixed-content model: You can specify only the names of the child elements that can occur. You cannot set the child elements' order or number of occurrences. And inside the mixed-content model, you cannot use the + , * , or ? operators. Because of these severe restrictions, I suggest avoiding the mixed-content model. You're almost always better off declaring a new element that can hold PCDATA and including that in a standard content model instead.
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