Web Design in a Nutshell, 3rd Edition

Explicit Attribute Values

XML (and therefore XHTML) does not support attribute minimization , the SGML practice in which certain attributes can be reduced to just the attribute value. So while HTML has many minimized attributes such as checked and nowrap, in XHTML, the values need to be explicitly declared as checked="checked" and nowrap="nowrap". Table 8-2 lists the attributes that were minimized in HTML but require values in XHTML.

Table 8-2. Explicit attribute values

checked="checked”	disabled="disabled”	noresize="noresize”
compact="compact”	ismap="ismap”	nowrap="nowrap”
declare="declare”	multiple="multiple”	readonly="readonly”
defer="defer”	noshade="noshade”	selected="selected”