Well, as you might expect, just as you use the DTD to define
valid elements, you also use the DTD to define valid element attributes.
We already went over attributes in the last section, but to refresh your
memory, we used the following example where STYLE and COLORING were
attributes of the SHOE element.
<SHOE STYLE = "SPECTATOR" COLORING = "BLACK_AND_WHITE">
To declare attributes in the DTD you use the general format of:
<!ATTLIST ELEMENT_NAME ATTRIBUTE_NAME TYPE DEFAULT_VALUE>
ELEMENT_NAME is equal to the element in which the attribute
appears such as "SHOE" in the example above.
ATTRIBUTE_NAME is equal to the name of the attribute such as
"STYLE" or "COLORING" in the example above.
DEFAULT_VALUE specifies the value that is used if none is specified by
the document author. there are several keywords that define standard
Of the four pieces, TYPE and DEFAULT_VALUE require some discusison.
Let's look at DEFAULT VALUES first.