Attributes are name/value pairs that you can use in start and empty tags to add additional information. We've already seen in Chapter 2, “Creating Well-Formed XML Documents,” that you can set up attributes as easily in XML as in HTML. Here's an example showing several attributes:
<CUSTOMER LAST_NAME="Smith" FIRST_NAME="Sam" DATE="October 15, 2003" PURCHASE="Tomatoes" PRICE="$1.25" NUMBER="8" />
In this case, I'm indicating that the customer's last name is Smith and first name is Sam, that the date of the current purchase is October 15, 2003, and that Sam purchased eight tomatoes for a total cost of $1.25.
Because you can declare elements in DTDs, you might expect that you can declare attributes as well, and you'd be right. ...